Patchwork [linuxppc-release] powerpc/pci-hotplug: fix init issue of rescanned pci device

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Submitter Yuanquan Chen
Date Dec. 5, 2012, 2:31 a.m.
Message ID <1354674717-14426-1-git-send-email-B41889@freescale.com>
Download mbox | patch
Permalink /patch/203771/
State Rejected
Headers show

Comments

Yuanquan Chen - Dec. 5, 2012, 2:31 a.m.
On powerpc arch, some fixup work of PCI/PCI-e device is just done during the
first scan at booting time. For the PCI/PCI-e device rescanned after linux OS
booting up, the fixup work won't be done, which leads to dma_set_mask error or
irq related issue in rescanned PCI/PCI-e device's driver. So, it does the same
fixup work for the rescanned device to avoid this issue.

Signed-off-by: Yuanquan Chen <B41889@freescale.com>
---
 arch/powerpc/kernel/pci-common.c |   20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
Benjamin Herrenschmidt - Dec. 5, 2012, 7:17 a.m.
On Wed, 2012-12-05 at 10:31 +0800, Yuanquan Chen wrote:
> On powerpc arch, some fixup work of PCI/PCI-e device is just done during the
> first scan at booting time. For the PCI/PCI-e device rescanned after linux OS
> booting up, the fixup work won't be done, which leads to dma_set_mask error or
> irq related issue in rescanned PCI/PCI-e device's driver. So, it does the same
> fixup work for the rescanned device to avoid this issue.

Hrm, the patch is a bit gross. First the code shouldn't be copy/pasted
that way but factored out.

I'm surprised also that is_added is false when pcibios_enable_device()
gets called ... that looks strange to me. At what point is that enable
happening in the hotplug sequence ?

How do you trigger the rescan anyway ?

I think the problem needs to be solve at a higher level, I'm adding
linux-pci & Bjorn to the CC list.

Cheers,
Ben.

> Signed-off-by: Yuanquan Chen <B41889@freescale.com>
> ---
>  arch/powerpc/kernel/pci-common.c |   20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
> index 7f94f76..f0fb070 100644
> --- a/arch/powerpc/kernel/pci-common.c
> +++ b/arch/powerpc/kernel/pci-common.c
> @@ -1496,6 +1496,26 @@ int pcibios_enable_device(struct pci_dev *dev, int mask)
>  		if (ppc_md.pcibios_enable_device_hook(dev))
>  			return -EINVAL;
>  
> +	if (!dev->is_added) {
> +		/* 
> +		 * Fixup NUMA node as it may not be setup yet by the generic
> +		 * code and is needed by the DMA init
> +		 */
> +		set_dev_node(&dev->dev, pcibus_to_node(dev->bus));
> +
> +		/* Hook up default DMA ops */
> +		set_dma_ops(&dev->dev, pci_dma_ops);
> +		set_dma_offset(&dev->dev, PCI_DRAM_OFFSET);
> +
> +		/* Additional platform DMA/iommu setup */
> +		if (ppc_md.pci_dma_dev_setup)
> +			ppc_md.pci_dma_dev_setup(dev);
> +
> +		/* Read default IRQs and fixup if necessary */
> +		pci_read_irq_line(dev);
> +		if (ppc_md.pci_irq_fixup)
> +			ppc_md.pci_irq_fixup(dev);
> +	}
>  	return pci_enable_resources(dev, mask);
>  }
>
Yuanquan Chen - Dec. 5, 2012, 8:20 a.m.
On 12/05/2012 03:17 PM, Benjamin Herrenschmidt wrote:
> On Wed, 2012-12-05 at 10:31 +0800, Yuanquan Chen wrote:
>> On powerpc arch, some fixup work of PCI/PCI-e device is just done during the
>> first scan at booting time. For the PCI/PCI-e device rescanned after linux OS
>> booting up, the fixup work won't be done, which leads to dma_set_mask error or
>> irq related issue in rescanned PCI/PCI-e device's driver. So, it does the same
>> fixup work for the rescanned device to avoid this issue.
> Hrm, the patch is a bit gross. First the code shouldn't be copy/pasted
> that way but factored out.
There's a judgement "if (!bus->is_added)" before calling of 
pcibios_fixup_bus
in pci_scan_child_bus, so for the rescanned device, the fixup won't execute,
which leads to fatal error in driver of rescanned device on freescale 
powerpc, no
this issues on x86 arch. Remove the judgement, let it to do the 
pcibios_fixup_bus
directly, the error won't occur for the rescanned device. But it's 
general code, not
proper to change here, so copy the pcibios_fixup_bus work to 
pcibios_enable_device.
> I'm surprised also that is_added is false when pcibios_enable_device()
> gets called ... that looks strange to me. At what point is that enable
> happening in the hotplug sequence ?
All devices are rescanned and then call the pci_enable_devices and 
pci_bus_add_devices.
The patch code will be called by pci_enable_devices. The "dev->is_added" 
is set in pci_bus_add_device
which is called by pci_bus_add_devices. So "dev->is_added" is false when 
checking it in pcibios_enable_device
for the rescanned device.
> How do you trigger the rescan anyway ?
Use the interface under /sys :
echo 1 > /sys/bus/pci/devices/xxx/remove

then echo 1 to the pci device which is the bus of the removed device
echo 1 > /sys/bus/pci/devices/xxxx/rescan
the removed device will be scanned and it's driver module will be loaded 
automatically.

Regards,
yuanquan
> I think the problem needs to be solve at a higher level, I'm adding
> linux-pci & Bjorn to the CC list.
>
> Cheers,
> Ben.
>
>> Signed-off-by: Yuanquan Chen <B41889@freescale.com>
>> ---
>>   arch/powerpc/kernel/pci-common.c |   20 ++++++++++++++++++++
>>   1 file changed, 20 insertions(+)
>>
>> diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
>> index 7f94f76..f0fb070 100644
>> --- a/arch/powerpc/kernel/pci-common.c
>> +++ b/arch/powerpc/kernel/pci-common.c
>> @@ -1496,6 +1496,26 @@ int pcibios_enable_device(struct pci_dev *dev, int mask)
>>   		if (ppc_md.pcibios_enable_device_hook(dev))
>>   			return -EINVAL;
>>   
>> +	if (!dev->is_added) {
>> +		/*
>> +		 * Fixup NUMA node as it may not be setup yet by the generic
>> +		 * code and is needed by the DMA init
>> +		 */
>> +		set_dev_node(&dev->dev, pcibus_to_node(dev->bus));
>> +
>> +		/* Hook up default DMA ops */
>> +		set_dma_ops(&dev->dev, pci_dma_ops);
>> +		set_dma_offset(&dev->dev, PCI_DRAM_OFFSET);
>> +
>> +		/* Additional platform DMA/iommu setup */
>> +		if (ppc_md.pci_dma_dev_setup)
>> +			ppc_md.pci_dma_dev_setup(dev);
>> +
>> +		/* Read default IRQs and fixup if necessary */
>> +		pci_read_irq_line(dev);
>> +		if (ppc_md.pci_irq_fixup)
>> +			ppc_md.pci_irq_fixup(dev);
>> +	}
>>   	return pci_enable_resources(dev, mask);
>>   }
>>   
>
>
>
>
Benjamin Herrenschmidt - Dec. 5, 2012, 8:26 a.m.
On Wed, 2012-12-05 at 16:20 +0800, Chen Yuanquan-B41889 wrote:
> On 12/05/2012 03:17 PM, Benjamin Herrenschmidt wrote:
> > On Wed, 2012-12-05 at 10:31 +0800, Yuanquan Chen wrote:
> >> On powerpc arch, some fixup work of PCI/PCI-e device is just done during the
> >> first scan at booting time. For the PCI/PCI-e device rescanned after linux OS
> >> booting up, the fixup work won't be done, which leads to dma_set_mask error or
> >> irq related issue in rescanned PCI/PCI-e device's driver. So, it does the same
> >> fixup work for the rescanned device to avoid this issue.
> > Hrm, the patch is a bit gross. First the code shouldn't be copy/pasted
> > that way but factored out.

Please, at least format your email properly so I can try to undertand
without needing aspirin.

> There's a judgement "if (!bus->is_added)" before calling of 
> pcibios_fixup_bus in pci_scan_child_bus, so for the rescanned device,
> the fixup won't execute, which leads to fatal error in driver of rescanned
> device on freescale  powerpc, no this issues on x86 arch.

First, none of that invalidates my statement that you shouldn't
duplicate a whole block of code like this. Even if your approach is
correct (which is debated separately), at the very least you should
factor the code out into a common function between the two copies.

> Remove the judgement, let it to do the pcibios_fixup_bus
> directly, the error won't occur for the rescanned device. But it's 
> general code, not proper to change here, so copy the pcibios_fixup_bus
> work to  pcibios_enable_device.
>
> > I'm surprised also that is_added is false when pcibios_enable_device()
> > gets called ... that looks strange to me. At what point is that enable
> > happening in the hotplug sequence ?
> All devices are rescanned and then call the pci_enable_devices and 
> pci_bus_add_devices.

Where ? How ? What is the sequence happening ? In any case, I think if
we need a proper fixup done per-device like that after scan we ought to
create a new hook at the generic level rather than that sort of hack.

> The patch code will be called by pci_enable_devices. The "dev->is_added" 
> is set in pci_bus_add_device
> which is called by pci_bus_add_devices. So "dev->is_added" is false when 
> checking it in pcibios_enable_device
> for the rescanned device.

Who calls pci_enable_device() in the rescan case ? Why isn't it left to
the driver ? I don't think we can rely on that behaviour not to change.

> > How do you trigger the rescan anyway ?
> Use the interface under /sys :
> echo 1 > /sys/bus/pci/devices/xxx/remove
> 
> then echo 1 to the pci device which is the bus of the removed device
> echo 1 > /sys/bus/pci/devices/xxxx/rescan
> the removed device will be scanned and it's driver module will be loaded 
> automatically.

Yeah this code path are known to be fishy. I think the problem is at the
generic abstraction level and that's where it needs to be fixed.

Cheers,
Ben.

> Regards,
> yuanquan
> > I think the problem needs to be solve at a higher level, I'm adding
> > linux-pci & Bjorn to the CC list.
> >
> > Cheers,
> > Ben.
> >
> >> Signed-off-by: Yuanquan Chen <B41889@freescale.com>
> >> ---
> >>   arch/powerpc/kernel/pci-common.c |   20 ++++++++++++++++++++
> >>   1 file changed, 20 insertions(+)
> >>
> >> diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
> >> index 7f94f76..f0fb070 100644
> >> --- a/arch/powerpc/kernel/pci-common.c
> >> +++ b/arch/powerpc/kernel/pci-common.c
> >> @@ -1496,6 +1496,26 @@ int pcibios_enable_device(struct pci_dev *dev, int mask)
> >>   		if (ppc_md.pcibios_enable_device_hook(dev))
> >>   			return -EINVAL;
> >>   
> >> +	if (!dev->is_added) {
> >> +		/*
> >> +		 * Fixup NUMA node as it may not be setup yet by the generic
> >> +		 * code and is needed by the DMA init
> >> +		 */
> >> +		set_dev_node(&dev->dev, pcibus_to_node(dev->bus));
> >> +
> >> +		/* Hook up default DMA ops */
> >> +		set_dma_ops(&dev->dev, pci_dma_ops);
> >> +		set_dma_offset(&dev->dev, PCI_DRAM_OFFSET);
> >> +
> >> +		/* Additional platform DMA/iommu setup */
> >> +		if (ppc_md.pci_dma_dev_setup)
> >> +			ppc_md.pci_dma_dev_setup(dev);
> >> +
> >> +		/* Read default IRQs and fixup if necessary */
> >> +		pci_read_irq_line(dev);
> >> +		if (ppc_md.pci_irq_fixup)
> >> +			ppc_md.pci_irq_fixup(dev);
> >> +	}
> >>   	return pci_enable_resources(dev, mask);
> >>   }
> >>   
> >
> >
> >
> >
>
Yuanquan Chen - Dec. 5, 2012, 9:29 a.m.
On 12/05/2012 04:26 PM, Benjamin Herrenschmidt wrote:
> On Wed, 2012-12-05 at 16:20 +0800, Chen Yuanquan-B41889 wrote:
>> On 12/05/2012 03:17 PM, Benjamin Herrenschmidt wrote:
>>> On Wed, 2012-12-05 at 10:31 +0800, Yuanquan Chen wrote:
>>>> On powerpc arch, some fixup work of PCI/PCI-e device is just done during the
>>>> first scan at booting time. For the PCI/PCI-e device rescanned after linux OS
>>>> booting up, the fixup work won't be done, which leads to dma_set_mask error or
>>>> irq related issue in rescanned PCI/PCI-e device's driver. So, it does the same
>>>> fixup work for the rescanned device to avoid this issue.
>>> Hrm, the patch is a bit gross. First the code shouldn't be copy/pasted
>>> that way but factored out.
> Please, at least format your email properly so I can try to undertand
> without needing aspirin.
>
>> There's a judgement "if (!bus->is_added)" before calling of
>> pcibios_fixup_bus in pci_scan_child_bus, so for the rescanned device,
>> the fixup won't execute, which leads to fatal error in driver of rescanned
>> device on freescale  powerpc, no this issues on x86 arch.
> First, none of that invalidates my statement that you shouldn't
> duplicate a whole block of code like this. Even if your approach is
> correct (which is debated separately), at the very least you should
> factor the code out into a common function between the two copies.
>
>> Remove the judgement, let it to do the pcibios_fixup_bus
>> directly, the error won't occur for the rescanned device. But it's
>> general code, not proper to change here, so copy the pcibios_fixup_bus
>> work to  pcibios_enable_device.
>>
>>> I'm surprised also that is_added is false when pcibios_enable_device()
>>> gets called ... that looks strange to me. At what point is that enable
>>> happening in the hotplug sequence ?
>> All devices are rescanned and then call the pci_enable_devices and
>> pci_bus_add_devices.
> Where ? How ? What is the sequence happening ? In any case, I think if
> we need a proper fixup done per-device like that after scan we ought to
> create a new hook at the generic level rather than that sort of hack.
>

echo 1 > rescan to trigger dev_rescan_store:

dev_rescan_store->pci_rescan_bus->pci_scan_child_bus, 
pci_assign_unassigned_bus_resources,
pci_enable_bridges, pci_bus_add_devices

pci_enable_bridges->pci_enable_device->__pci_enable_device_flags->do_pci_enable_device->
pcibios_enable_device

pci_bus_add_devices->pci_bus_add_device->"dev->is_added = 1"

Yeah, it's general fixup code for every rescanned PCI/PCI-e device on 
powerpc at runtime. So if
we want to call it in a ppc_md member, we need to wrap it as a function 
and assign it in every ppc_md,
it isn't proper for the general code.

Regards,
yuanquan

>> The patch code will be called by pci_enable_devices. The "dev->is_added"
>> is set in pci_bus_add_device
>> which is called by pci_bus_add_devices. So "dev->is_added" is false when
>> checking it in pcibios_enable_device
>> for the rescanned device.
> Who calls pci_enable_device() in the rescan case ? Why isn't it left to
> the driver ? I don't think we can rely on that behaviour not to change.
>
>>> How do you trigger the rescan anyway ?
>> Use the interface under /sys :
>> echo 1 > /sys/bus/pci/devices/xxx/remove
>>
>> then echo 1 to the pci device which is the bus of the removed device
>> echo 1 > /sys/bus/pci/devices/xxxx/rescan
>> the removed device will be scanned and it's driver module will be loaded
>> automatically.
> Yeah this code path are known to be fishy. I think the problem is at the
> generic abstraction level and that's where it needs to be fixed.
>
> Cheers,
> Ben.
>
>> Regards,
>> yuanquan
>>> I think the problem needs to be solve at a higher level, I'm adding
>>> linux-pci & Bjorn to the CC list.
>>>
>>> Cheers,
>>> Ben.
>>>
>>>> Signed-off-by: Yuanquan Chen <B41889@freescale.com>
>>>> ---
>>>>    arch/powerpc/kernel/pci-common.c |   20 ++++++++++++++++++++
>>>>    1 file changed, 20 insertions(+)
>>>>
>>>> diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
>>>> index 7f94f76..f0fb070 100644
>>>> --- a/arch/powerpc/kernel/pci-common.c
>>>> +++ b/arch/powerpc/kernel/pci-common.c
>>>> @@ -1496,6 +1496,26 @@ int pcibios_enable_device(struct pci_dev *dev, int mask)
>>>>    		if (ppc_md.pcibios_enable_device_hook(dev))
>>>>    			return -EINVAL;
>>>>    
>>>> +	if (!dev->is_added) {
>>>> +		/*
>>>> +		 * Fixup NUMA node as it may not be setup yet by the generic
>>>> +		 * code and is needed by the DMA init
>>>> +		 */
>>>> +		set_dev_node(&dev->dev, pcibus_to_node(dev->bus));
>>>> +
>>>> +		/* Hook up default DMA ops */
>>>> +		set_dma_ops(&dev->dev, pci_dma_ops);
>>>> +		set_dma_offset(&dev->dev, PCI_DRAM_OFFSET);
>>>> +
>>>> +		/* Additional platform DMA/iommu setup */
>>>> +		if (ppc_md.pci_dma_dev_setup)
>>>> +			ppc_md.pci_dma_dev_setup(dev);
>>>> +
>>>> +		/* Read default IRQs and fixup if necessary */
>>>> +		pci_read_irq_line(dev);
>>>> +		if (ppc_md.pci_irq_fixup)
>>>> +			ppc_md.pci_irq_fixup(dev);
>>>> +	}
>>>>    	return pci_enable_resources(dev, mask);
>>>>    }
>>>>    
>>>
>>>
>>>
>
>
>
>
Bjorn Helgaas - Dec. 5, 2012, 9:30 p.m.
On Wed, Dec 5, 2012 at 2:29 AM, Chen Yuanquan-B41889
<B41889@freescale.com> wrote:
> On 12/05/2012 04:26 PM, Benjamin Herrenschmidt wrote:
>>
>> On Wed, 2012-12-05 at 16:20 +0800, Chen Yuanquan-B41889 wrote:
>>>
>>> On 12/05/2012 03:17 PM, Benjamin Herrenschmidt wrote:
>>>>
>>>> On Wed, 2012-12-05 at 10:31 +0800, Yuanquan Chen wrote:
>>>>>
>>>>> On powerpc arch, some fixup work of PCI/PCI-e device is just done
>>>>> during the
>>>>> first scan at booting time. For the PCI/PCI-e device rescanned after
>>>>> linux OS
>>>>> booting up, the fixup work won't be done, which leads to dma_set_mask
>>>>> error or
>>>>> irq related issue in rescanned PCI/PCI-e device's driver. So, it does
>>>>> the same
>>>>> fixup work for the rescanned device to avoid this issue.
>>>>
>>>> Hrm, the patch is a bit gross. First the code shouldn't be copy/pasted
>>>> that way but factored out.
>>
>> Please, at least format your email properly so I can try to undertand
>> without needing aspirin.
>>
>>> There's a judgement "if (!bus->is_added)" before calling of
>>> pcibios_fixup_bus in pci_scan_child_bus, so for the rescanned device,
>>> the fixup won't execute, which leads to fatal error in driver of
>>> rescanned
>>> device on freescale  powerpc, no this issues on x86 arch.
>>
>> First, none of that invalidates my statement that you shouldn't
>> duplicate a whole block of code like this. Even if your approach is
>> correct (which is debated separately), at the very least you should
>> factor the code out into a common function between the two copies.
>>
>>> Remove the judgement, let it to do the pcibios_fixup_bus
>>> directly, the error won't occur for the rescanned device. But it's
>>> general code, not proper to change here, so copy the pcibios_fixup_bus
>>> work to  pcibios_enable_device.
>>>
>>>> I'm surprised also that is_added is false when pcibios_enable_device()
>>>> gets called ... that looks strange to me. At what point is that enable
>>>> happening in the hotplug sequence ?
>>>
>>> All devices are rescanned and then call the pci_enable_devices and
>>> pci_bus_add_devices.
>>
>> Where ? How ? What is the sequence happening ? In any case, I think if
>> we need a proper fixup done per-device like that after scan we ought to
>> create a new hook at the generic level rather than that sort of hack.
>>
>
> echo 1 > rescan to trigger dev_rescan_store:
>
> dev_rescan_store->pci_rescan_bus->pci_scan_child_bus,
> pci_assign_unassigned_bus_resources,
> pci_enable_bridges, pci_bus_add_devices
>
> pci_enable_bridges->pci_enable_device->__pci_enable_device_flags->do_pci_enable_device->
> pcibios_enable_device
>
> pci_bus_add_devices->pci_bus_add_device->"dev->is_added = 1"
>
> Yeah, it's general fixup code for every rescanned PCI/PCI-e device on
> powerpc at runtime. So if
> we want to call it in a ppc_md member, we need to wrap it as a function and
> assign it in every ppc_md,
> it isn't proper for the general code.
>
> Regards,
> yuanquan
>
>
>>> The patch code will be called by pci_enable_devices. The "dev->is_added"
>>> is set in pci_bus_add_device
>>> which is called by pci_bus_add_devices. So "dev->is_added" is false when
>>> checking it in pcibios_enable_device
>>> for the rescanned device.
>>
>> Who calls pci_enable_device() in the rescan case ? Why isn't it left to
>> the driver ? I don't think we can rely on that behaviour not to change.
>>
>>>> How do you trigger the rescan anyway ?
>>>
>>> Use the interface under /sys :
>>> echo 1 > /sys/bus/pci/devices/xxx/remove
>>>
>>> then echo 1 to the pci device which is the bus of the removed device
>>> echo 1 > /sys/bus/pci/devices/xxxx/rescan
>>> the removed device will be scanned and it's driver module will be loaded
>>> automatically.
>>
>> Yeah this code path are known to be fishy. I think the problem is at the
>> generic abstraction level and that's where it needs to be fixed.
>>
>> Cheers,
>> Ben.
>>
>>> Regards,
>>> yuanquan
>>>>
>>>> I think the problem needs to be solve at a higher level, I'm adding
>>>> linux-pci & Bjorn to the CC list.
>>>>
>>>> Cheers,
>>>> Ben.
>>>>
>>>>> Signed-off-by: Yuanquan Chen <B41889@freescale.com>
>>>>> ---
>>>>>    arch/powerpc/kernel/pci-common.c |   20 ++++++++++++++++++++
>>>>>    1 file changed, 20 insertions(+)
>>>>>
>>>>> diff --git a/arch/powerpc/kernel/pci-common.c
>>>>> b/arch/powerpc/kernel/pci-common.c
>>>>> index 7f94f76..f0fb070 100644
>>>>> --- a/arch/powerpc/kernel/pci-common.c
>>>>> +++ b/arch/powerpc/kernel/pci-common.c
>>>>> @@ -1496,6 +1496,26 @@ int pcibios_enable_device(struct pci_dev *dev,
>>>>> int mask)
>>>>>                 if (ppc_md.pcibios_enable_device_hook(dev))
>>>>>                         return -EINVAL;
>>>>>    +    if (!dev->is_added) {
>>>>> +               /*
>>>>> +                * Fixup NUMA node as it may not be setup yet by the
>>>>> generic
>>>>> +                * code and is needed by the DMA init
>>>>> +                */
>>>>> +               set_dev_node(&dev->dev, pcibus_to_node(dev->bus));
>>>>> +
>>>>> +               /* Hook up default DMA ops */
>>>>> +               set_dma_ops(&dev->dev, pci_dma_ops);
>>>>> +               set_dma_offset(&dev->dev, PCI_DRAM_OFFSET);
>>>>> +
>>>>> +               /* Additional platform DMA/iommu setup */
>>>>> +               if (ppc_md.pci_dma_dev_setup)
>>>>> +                       ppc_md.pci_dma_dev_setup(dev);
>>>>> +
>>>>> +               /* Read default IRQs and fixup if necessary */
>>>>> +               pci_read_irq_line(dev);
>>>>> +               if (ppc_md.pci_irq_fixup)
>>>>> +                       ppc_md.pci_irq_fixup(dev);
>>>>> +       }
>>>>>         return pci_enable_resources(dev, mask);
>>>>>    }

Is this the same issue Hiroo MATSUMOTO was working on earlier?
(http://comments.gmane.org/gmane.linux.ports.ppc.embedded/50080)

We went round and round on those patches (partly my fault for
excessive bike-shedding), and then we stalled out because of an
ordering issue with CardBus init and an IRQ quirk.

Here's the last status I remember:
http://marc.info/?l=linux-pci&m=135006501620378&w=2

Bjorn
Yuanquan Chen - Dec. 6, 2012, 11:23 a.m.
On 12/06/2012 05:30 AM, Bjorn Helgaas wrote:
> On Wed, Dec 5, 2012 at 2:29 AM, Chen Yuanquan-B41889
> <B41889@freescale.com> wrote:
>> On 12/05/2012 04:26 PM, Benjamin Herrenschmidt wrote:
>>> On Wed, 2012-12-05 at 16:20 +0800, Chen Yuanquan-B41889 wrote:
>>>> On 12/05/2012 03:17 PM, Benjamin Herrenschmidt wrote:
>>>>> On Wed, 2012-12-05 at 10:31 +0800, Yuanquan Chen wrote:
>>>>>> On powerpc arch, some fixup work of PCI/PCI-e device is just done
>>>>>> during the
>>>>>> first scan at booting time. For the PCI/PCI-e device rescanned after
>>>>>> linux OS
>>>>>> booting up, the fixup work won't be done, which leads to dma_set_mask
>>>>>> error or
>>>>>> irq related issue in rescanned PCI/PCI-e device's driver. So, it does
>>>>>> the same
>>>>>> fixup work for the rescanned device to avoid this issue.
>>>>> Hrm, the patch is a bit gross. First the code shouldn't be copy/pasted
>>>>> that way but factored out.
>>> Please, at least format your email properly so I can try to undertand
>>> without needing aspirin.
>>>
>>>> There's a judgement "if (!bus->is_added)" before calling of
>>>> pcibios_fixup_bus in pci_scan_child_bus, so for the rescanned device,
>>>> the fixup won't execute, which leads to fatal error in driver of
>>>> rescanned
>>>> device on freescale  powerpc, no this issues on x86 arch.
>>> First, none of that invalidates my statement that you shouldn't
>>> duplicate a whole block of code like this. Even if your approach is
>>> correct (which is debated separately), at the very least you should
>>> factor the code out into a common function between the two copies.
>>>
>>>> Remove the judgement, let it to do the pcibios_fixup_bus
>>>> directly, the error won't occur for the rescanned device. But it's
>>>> general code, not proper to change here, so copy the pcibios_fixup_bus
>>>> work to  pcibios_enable_device.
>>>>
>>>>> I'm surprised also that is_added is false when pcibios_enable_device()
>>>>> gets called ... that looks strange to me. At what point is that enable
>>>>> happening in the hotplug sequence ?
>>>> All devices are rescanned and then call the pci_enable_devices and
>>>> pci_bus_add_devices.
>>> Where ? How ? What is the sequence happening ? In any case, I think if
>>> we need a proper fixup done per-device like that after scan we ought to
>>> create a new hook at the generic level rather than that sort of hack.
>>>
>> echo 1 > rescan to trigger dev_rescan_store:
>>
>> dev_rescan_store->pci_rescan_bus->pci_scan_child_bus,
>> pci_assign_unassigned_bus_resources,
>> pci_enable_bridges, pci_bus_add_devices
>>
>> pci_enable_bridges->pci_enable_device->__pci_enable_device_flags->do_pci_enable_device->
>> pcibios_enable_device
>>
>> pci_bus_add_devices->pci_bus_add_device->"dev->is_added = 1"
>>
>> Yeah, it's general fixup code for every rescanned PCI/PCI-e device on
>> powerpc at runtime. So if
>> we want to call it in a ppc_md member, we need to wrap it as a function and
>> assign it in every ppc_md,
>> it isn't proper for the general code.
>>
>> Regards,
>> yuanquan
>>
>>
>>>> The patch code will be called by pci_enable_devices. The "dev->is_added"
>>>> is set in pci_bus_add_device
>>>> which is called by pci_bus_add_devices. So "dev->is_added" is false when
>>>> checking it in pcibios_enable_device
>>>> for the rescanned device.
>>> Who calls pci_enable_device() in the rescan case ? Why isn't it left to
>>> the driver ? I don't think we can rely on that behaviour not to change.
>>>
>>>>> How do you trigger the rescan anyway ?
>>>> Use the interface under /sys :
>>>> echo 1 > /sys/bus/pci/devices/xxx/remove
>>>>
>>>> then echo 1 to the pci device which is the bus of the removed device
>>>> echo 1 > /sys/bus/pci/devices/xxxx/rescan
>>>> the removed device will be scanned and it's driver module will be loaded
>>>> automatically.
>>> Yeah this code path are known to be fishy. I think the problem is at the
>>> generic abstraction level and that's where it needs to be fixed.
>>>
>>> Cheers,
>>> Ben.
>>>
>>>> Regards,
>>>> yuanquan
>>>>> I think the problem needs to be solve at a higher level, I'm adding
>>>>> linux-pci & Bjorn to the CC list.
>>>>>
>>>>> Cheers,
>>>>> Ben.
>>>>>
>>>>>> Signed-off-by: Yuanquan Chen <B41889@freescale.com>
>>>>>> ---
>>>>>>     arch/powerpc/kernel/pci-common.c |   20 ++++++++++++++++++++
>>>>>>     1 file changed, 20 insertions(+)
>>>>>>
>>>>>> diff --git a/arch/powerpc/kernel/pci-common.c
>>>>>> b/arch/powerpc/kernel/pci-common.c
>>>>>> index 7f94f76..f0fb070 100644
>>>>>> --- a/arch/powerpc/kernel/pci-common.c
>>>>>> +++ b/arch/powerpc/kernel/pci-common.c
>>>>>> @@ -1496,6 +1496,26 @@ int pcibios_enable_device(struct pci_dev *dev,
>>>>>> int mask)
>>>>>>                  if (ppc_md.pcibios_enable_device_hook(dev))
>>>>>>                          return -EINVAL;
>>>>>>     +    if (!dev->is_added) {
>>>>>> +               /*
>>>>>> +                * Fixup NUMA node as it may not be setup yet by the
>>>>>> generic
>>>>>> +                * code and is needed by the DMA init
>>>>>> +                */
>>>>>> +               set_dev_node(&dev->dev, pcibus_to_node(dev->bus));
>>>>>> +
>>>>>> +               /* Hook up default DMA ops */
>>>>>> +               set_dma_ops(&dev->dev, pci_dma_ops);
>>>>>> +               set_dma_offset(&dev->dev, PCI_DRAM_OFFSET);
>>>>>> +
>>>>>> +               /* Additional platform DMA/iommu setup */
>>>>>> +               if (ppc_md.pci_dma_dev_setup)
>>>>>> +                       ppc_md.pci_dma_dev_setup(dev);
>>>>>> +
>>>>>> +               /* Read default IRQs and fixup if necessary */
>>>>>> +               pci_read_irq_line(dev);
>>>>>> +               if (ppc_md.pci_irq_fixup)
>>>>>> +                       ppc_md.pci_irq_fixup(dev);
>>>>>> +       }
>>>>>>          return pci_enable_resources(dev, mask);
>>>>>>     }
> Is this the same issue Hiroo MATSUMOTO was working on earlier?
> (http://comments.gmane.org/gmane.linux.ports.ppc.embedded/50080)

Yeah, that's the exact problem I encountered. Please push it forward.

Thanks,
yuanquan

> We went round and round on those patches (partly my fault for
> excessive bike-shedding), and then we stalled out because of an
> ordering issue with CardBus init and an IRQ quirk.
>
> Here's the last status I remember:
> http://marc.info/?l=linux-pci&m=135006501620378&w=2
>
> Bjorn
>
>
>
Bjorn Helgaas - Dec. 7, 2012, 9:15 p.m.
On Thu, Dec 6, 2012 at 4:23 AM, Chen Yuanquan-B41889
<B41889@freescale.com> wrote:
> On 12/06/2012 05:30 AM, Bjorn Helgaas wrote:
>>
>> On Wed, Dec 5, 2012 at 2:29 AM, Chen Yuanquan-B41889
>> <B41889@freescale.com> wrote:
>>>
>>> On 12/05/2012 04:26 PM, Benjamin Herrenschmidt wrote:
>>>>
>>>> On Wed, 2012-12-05 at 16:20 +0800, Chen Yuanquan-B41889 wrote:
>>>>>
>>>>> On 12/05/2012 03:17 PM, Benjamin Herrenschmidt wrote:
>>>>>>
>>>>>> On Wed, 2012-12-05 at 10:31 +0800, Yuanquan Chen wrote:
>>>>>>>
>>>>>>> On powerpc arch, some fixup work of PCI/PCI-e device is just done
>>>>>>> during the
>>>>>>> first scan at booting time. For the PCI/PCI-e device rescanned after
>>>>>>> linux OS
>>>>>>> booting up, the fixup work won't be done, which leads to dma_set_mask
>>>>>>> error or
>>>>>>> irq related issue in rescanned PCI/PCI-e device's driver. So, it does
>>>>>>> the same
>>>>>>> fixup work for the rescanned device to avoid this issue.
>>>>>>
>>>>>> Hrm, the patch is a bit gross. First the code shouldn't be copy/pasted
>>>>>> that way but factored out.
>>>>
>>>> Please, at least format your email properly so I can try to undertand
>>>> without needing aspirin.
>>>>
>>>>> There's a judgement "if (!bus->is_added)" before calling of
>>>>> pcibios_fixup_bus in pci_scan_child_bus, so for the rescanned device,
>>>>> the fixup won't execute, which leads to fatal error in driver of
>>>>> rescanned
>>>>> device on freescale  powerpc, no this issues on x86 arch.
>>>>
>>>> First, none of that invalidates my statement that you shouldn't
>>>> duplicate a whole block of code like this. Even if your approach is
>>>> correct (which is debated separately), at the very least you should
>>>> factor the code out into a common function between the two copies.
>>>>
>>>>> Remove the judgement, let it to do the pcibios_fixup_bus
>>>>> directly, the error won't occur for the rescanned device. But it's
>>>>> general code, not proper to change here, so copy the pcibios_fixup_bus
>>>>> work to  pcibios_enable_device.
>>>>>
>>>>>> I'm surprised also that is_added is false when pcibios_enable_device()
>>>>>> gets called ... that looks strange to me. At what point is that enable
>>>>>> happening in the hotplug sequence ?
>>>>>
>>>>> All devices are rescanned and then call the pci_enable_devices and
>>>>> pci_bus_add_devices.
>>>>
>>>> Where ? How ? What is the sequence happening ? In any case, I think if
>>>> we need a proper fixup done per-device like that after scan we ought to
>>>> create a new hook at the generic level rather than that sort of hack.
>>>>
>>> echo 1 > rescan to trigger dev_rescan_store:
>>>
>>> dev_rescan_store->pci_rescan_bus->pci_scan_child_bus,
>>> pci_assign_unassigned_bus_resources,
>>> pci_enable_bridges, pci_bus_add_devices
>>>
>>>
>>> pci_enable_bridges->pci_enable_device->__pci_enable_device_flags->do_pci_enable_device->
>>> pcibios_enable_device
>>>
>>> pci_bus_add_devices->pci_bus_add_device->"dev->is_added = 1"
>>>
>>> Yeah, it's general fixup code for every rescanned PCI/PCI-e device on
>>> powerpc at runtime. So if
>>> we want to call it in a ppc_md member, we need to wrap it as a function
>>> and
>>> assign it in every ppc_md,
>>> it isn't proper for the general code.
>>>
>>> Regards,
>>> yuanquan
>>>
>>>
>>>>> The patch code will be called by pci_enable_devices. The
>>>>> "dev->is_added"
>>>>> is set in pci_bus_add_device
>>>>> which is called by pci_bus_add_devices. So "dev->is_added" is false
>>>>> when
>>>>> checking it in pcibios_enable_device
>>>>> for the rescanned device.
>>>>
>>>> Who calls pci_enable_device() in the rescan case ? Why isn't it left to
>>>> the driver ? I don't think we can rely on that behaviour not to change.
>>>>
>>>>>> How do you trigger the rescan anyway ?
>>>>>
>>>>> Use the interface under /sys :
>>>>> echo 1 > /sys/bus/pci/devices/xxx/remove
>>>>>
>>>>> then echo 1 to the pci device which is the bus of the removed device
>>>>> echo 1 > /sys/bus/pci/devices/xxxx/rescan
>>>>> the removed device will be scanned and it's driver module will be
>>>>> loaded
>>>>> automatically.
>>>>
>>>> Yeah this code path are known to be fishy. I think the problem is at the
>>>> generic abstraction level and that's where it needs to be fixed.
>>>>
>>>> Cheers,
>>>> Ben.
>>>>
>>>>> Regards,
>>>>> yuanquan
>>>>>>
>>>>>> I think the problem needs to be solve at a higher level, I'm adding
>>>>>> linux-pci & Bjorn to the CC list.
>>>>>>
>>>>>> Cheers,
>>>>>> Ben.
>>>>>>
>>>>>>> Signed-off-by: Yuanquan Chen <B41889@freescale.com>
>>>>>>> ---
>>>>>>>     arch/powerpc/kernel/pci-common.c |   20 ++++++++++++++++++++
>>>>>>>     1 file changed, 20 insertions(+)
>>>>>>>
>>>>>>> diff --git a/arch/powerpc/kernel/pci-common.c
>>>>>>> b/arch/powerpc/kernel/pci-common.c
>>>>>>> index 7f94f76..f0fb070 100644
>>>>>>> --- a/arch/powerpc/kernel/pci-common.c
>>>>>>> +++ b/arch/powerpc/kernel/pci-common.c
>>>>>>> @@ -1496,6 +1496,26 @@ int pcibios_enable_device(struct pci_dev *dev,
>>>>>>> int mask)
>>>>>>>                  if (ppc_md.pcibios_enable_device_hook(dev))
>>>>>>>                          return -EINVAL;
>>>>>>>     +    if (!dev->is_added) {
>>>>>>> +               /*
>>>>>>> +                * Fixup NUMA node as it may not be setup yet by the
>>>>>>> generic
>>>>>>> +                * code and is needed by the DMA init
>>>>>>> +                */
>>>>>>> +               set_dev_node(&dev->dev, pcibus_to_node(dev->bus));
>>>>>>> +
>>>>>>> +               /* Hook up default DMA ops */
>>>>>>> +               set_dma_ops(&dev->dev, pci_dma_ops);
>>>>>>> +               set_dma_offset(&dev->dev, PCI_DRAM_OFFSET);
>>>>>>> +
>>>>>>> +               /* Additional platform DMA/iommu setup */
>>>>>>> +               if (ppc_md.pci_dma_dev_setup)
>>>>>>> +                       ppc_md.pci_dma_dev_setup(dev);
>>>>>>> +
>>>>>>> +               /* Read default IRQs and fixup if necessary */
>>>>>>> +               pci_read_irq_line(dev);
>>>>>>> +               if (ppc_md.pci_irq_fixup)
>>>>>>> +                       ppc_md.pci_irq_fixup(dev);
>>>>>>> +       }
>>>>>>>          return pci_enable_resources(dev, mask);
>>>>>>>     }
>>
>> Is this the same issue Hiroo MATSUMOTO was working on earlier?
>> (http://comments.gmane.org/gmane.linux.ports.ppc.embedded/50080)
>
>
> Yeah, that's the exact problem I encountered. Please push it forward.

Well, as I mentioned, there are unresolved issues, so it's not just a
matter of applying the most recent patch.  If you're interested in
this problem and have some hardware to test, you can help by looking
into some of the things I mentioned in the message at the URL below.

>> We went round and round on those patches (partly my fault for
>> excessive bike-shedding), and then we stalled out because of an
>> ordering issue with CardBus init and an IRQ quirk.
>>
>> Here's the last status I remember:
>> http://marc.info/?l=linux-pci&m=135006501620378&w=2
>>
>> Bjorn
>>
>>
>>
>
>
Yuanquan Chen - April 1, 2013, 10:29 a.m.
On 12/08/2012 05:15 AM, Bjorn Helgaas wrote:
> On Thu, Dec 6, 2012 at 4:23 AM, Chen Yuanquan-B41889
> <B41889@freescale.com> wrote:
>> On 12/06/2012 05:30 AM, Bjorn Helgaas wrote:
>>> On Wed, Dec 5, 2012 at 2:29 AM, Chen Yuanquan-B41889
>>> <B41889@freescale.com> wrote:
>>>> On 12/05/2012 04:26 PM, Benjamin Herrenschmidt wrote:
>>>>> On Wed, 2012-12-05 at 16:20 +0800, Chen Yuanquan-B41889 wrote:
>>>>>> On 12/05/2012 03:17 PM, Benjamin Herrenschmidt wrote:
>>>>>>> On Wed, 2012-12-05 at 10:31 +0800, Yuanquan Chen wrote:
>>>>>>>> On powerpc arch, some fixup work of PCI/PCI-e device is just done
>>>>>>>> during the
>>>>>>>> first scan at booting time. For the PCI/PCI-e device rescanned after
>>>>>>>> linux OS
>>>>>>>> booting up, the fixup work won't be done, which leads to dma_set_mask
>>>>>>>> error or
>>>>>>>> irq related issue in rescanned PCI/PCI-e device's driver. So, it does
>>>>>>>> the same
>>>>>>>> fixup work for the rescanned device to avoid this issue.
>>>>>>> Hrm, the patch is a bit gross. First the code shouldn't be copy/pasted
>>>>>>> that way but factored out.
>>>>> Please, at least format your email properly so I can try to undertand
>>>>> without needing aspirin.
>>>>>
>>>>>> There's a judgement "if (!bus->is_added)" before calling of
>>>>>> pcibios_fixup_bus in pci_scan_child_bus, so for the rescanned device,
>>>>>> the fixup won't execute, which leads to fatal error in driver of
>>>>>> rescanned
>>>>>> device on freescale  powerpc, no this issues on x86 arch.
>>>>> First, none of that invalidates my statement that you shouldn't
>>>>> duplicate a whole block of code like this. Even if your approach is
>>>>> correct (which is debated separately), at the very least you should
>>>>> factor the code out into a common function between the two copies.
>>>>>
>>>>>> Remove the judgement, let it to do the pcibios_fixup_bus
>>>>>> directly, the error won't occur for the rescanned device. But it's
>>>>>> general code, not proper to change here, so copy the pcibios_fixup_bus
>>>>>> work to  pcibios_enable_device.
>>>>>>
>>>>>>> I'm surprised also that is_added is false when pcibios_enable_device()
>>>>>>> gets called ... that looks strange to me. At what point is that enable
>>>>>>> happening in the hotplug sequence ?
>>>>>> All devices are rescanned and then call the pci_enable_devices and
>>>>>> pci_bus_add_devices.
>>>>> Where ? How ? What is the sequence happening ? In any case, I think if
>>>>> we need a proper fixup done per-device like that after scan we ought to
>>>>> create a new hook at the generic level rather than that sort of hack.
>>>>>
>>>> echo 1 > rescan to trigger dev_rescan_store:
>>>>
>>>> dev_rescan_store->pci_rescan_bus->pci_scan_child_bus,
>>>> pci_assign_unassigned_bus_resources,
>>>> pci_enable_bridges, pci_bus_add_devices
>>>>
>>>>
>>>> pci_enable_bridges->pci_enable_device->__pci_enable_device_flags->do_pci_enable_device->
>>>> pcibios_enable_device
>>>>
>>>> pci_bus_add_devices->pci_bus_add_device->"dev->is_added = 1"
>>>>
>>>> Yeah, it's general fixup code for every rescanned PCI/PCI-e device on
>>>> powerpc at runtime. So if
>>>> we want to call it in a ppc_md member, we need to wrap it as a function
>>>> and
>>>> assign it in every ppc_md,
>>>> it isn't proper for the general code.
>>>>
>>>> Regards,
>>>> yuanquan
>>>>
>>>>
>>>>>> The patch code will be called by pci_enable_devices. The
>>>>>> "dev->is_added"
>>>>>> is set in pci_bus_add_device
>>>>>> which is called by pci_bus_add_devices. So "dev->is_added" is false
>>>>>> when
>>>>>> checking it in pcibios_enable_device
>>>>>> for the rescanned device.
>>>>> Who calls pci_enable_device() in the rescan case ? Why isn't it left to
>>>>> the driver ? I don't think we can rely on that behaviour not to change.
>>>>>
>>>>>>> How do you trigger the rescan anyway ?
>>>>>> Use the interface under /sys :
>>>>>> echo 1 > /sys/bus/pci/devices/xxx/remove
>>>>>>
>>>>>> then echo 1 to the pci device which is the bus of the removed device
>>>>>> echo 1 > /sys/bus/pci/devices/xxxx/rescan
>>>>>> the removed device will be scanned and it's driver module will be
>>>>>> loaded
>>>>>> automatically.
>>>>> Yeah this code path are known to be fishy. I think the problem is at the
>>>>> generic abstraction level and that's where it needs to be fixed.
>>>>>
>>>>> Cheers,
>>>>> Ben.
>>>>>
>>>>>> Regards,
>>>>>> yuanquan
>>>>>>> I think the problem needs to be solve at a higher level, I'm adding
>>>>>>> linux-pci & Bjorn to the CC list.
>>>>>>>
>>>>>>> Cheers,
>>>>>>> Ben.
>>>>>>>
>>>>>>>> Signed-off-by: Yuanquan Chen <B41889@freescale.com>
>>>>>>>> ---
>>>>>>>>      arch/powerpc/kernel/pci-common.c |   20 ++++++++++++++++++++
>>>>>>>>      1 file changed, 20 insertions(+)
>>>>>>>>
>>>>>>>> diff --git a/arch/powerpc/kernel/pci-common.c
>>>>>>>> b/arch/powerpc/kernel/pci-common.c
>>>>>>>> index 7f94f76..f0fb070 100644
>>>>>>>> --- a/arch/powerpc/kernel/pci-common.c
>>>>>>>> +++ b/arch/powerpc/kernel/pci-common.c
>>>>>>>> @@ -1496,6 +1496,26 @@ int pcibios_enable_device(struct pci_dev *dev,
>>>>>>>> int mask)
>>>>>>>>                   if (ppc_md.pcibios_enable_device_hook(dev))
>>>>>>>>                           return -EINVAL;
>>>>>>>>      +    if (!dev->is_added) {
>>>>>>>> +               /*
>>>>>>>> +                * Fixup NUMA node as it may not be setup yet by the
>>>>>>>> generic
>>>>>>>> +                * code and is needed by the DMA init
>>>>>>>> +                */
>>>>>>>> +               set_dev_node(&dev->dev, pcibus_to_node(dev->bus));
>>>>>>>> +
>>>>>>>> +               /* Hook up default DMA ops */
>>>>>>>> +               set_dma_ops(&dev->dev, pci_dma_ops);
>>>>>>>> +               set_dma_offset(&dev->dev, PCI_DRAM_OFFSET);
>>>>>>>> +
>>>>>>>> +               /* Additional platform DMA/iommu setup */
>>>>>>>> +               if (ppc_md.pci_dma_dev_setup)
>>>>>>>> +                       ppc_md.pci_dma_dev_setup(dev);
>>>>>>>> +
>>>>>>>> +               /* Read default IRQs and fixup if necessary */
>>>>>>>> +               pci_read_irq_line(dev);
>>>>>>>> +               if (ppc_md.pci_irq_fixup)
>>>>>>>> +                       ppc_md.pci_irq_fixup(dev);
>>>>>>>> +       }
>>>>>>>>           return pci_enable_resources(dev, mask);
>>>>>>>>      }
>>> Is this the same issue Hiroo MATSUMOTO was working on earlier?
>>> (http://comments.gmane.org/gmane.linux.ports.ppc.embedded/50080)
>>
>> Yeah, that's the exact problem I encountered. Please push it forward.
> Well, as I mentioned, there are unresolved issues, so it's not just a
> matter of applying the most recent patch.  If you're interested in
> this problem and have some hardware to test, you can help by looking
> into some of the things I mentioned in the message at the URL below.

Hi Helgaas , Matsumoto,

Do you have new update about this issue? I will go on to investigate 
this issue in the next
days.

Thanks,
Yuanquan

>>> We went round and round on those patches (partly my fault for
>>> excessive bike-shedding), and then we stalled out because of an
>>> ordering issue with CardBus init and an IRQ quirk.
>>>
>>> Here's the last status I remember:
>>> http://marc.info/?l=linux-pci&m=135006501620378&w=2
>>>
>>> Bjorn
>>>
>>>
>>>
>>
>
>
Bjorn Helgaas - April 1, 2013, 4:29 p.m.
On Mon, Apr 1, 2013 at 4:29 AM, Chen Yuanquan-B41889
<B41889@freescale.com> wrote:
> On 12/08/2012 05:15 AM, Bjorn Helgaas wrote:
>>
>> On Thu, Dec 6, 2012 at 4:23 AM, Chen Yuanquan-B41889
>> <B41889@freescale.com> wrote:
>>>
>>> On 12/06/2012 05:30 AM, Bjorn Helgaas wrote:
>>>>
>>>> On Wed, Dec 5, 2012 at 2:29 AM, Chen Yuanquan-B41889
>>>> <B41889@freescale.com> wrote:
>>>>>
>>>>> On 12/05/2012 04:26 PM, Benjamin Herrenschmidt wrote:
>>>>>>
>>>>>> On Wed, 2012-12-05 at 16:20 +0800, Chen Yuanquan-B41889 wrote:
>>>>>>>
>>>>>>> On 12/05/2012 03:17 PM, Benjamin Herrenschmidt wrote:
>>>>>>>>
>>>>>>>> On Wed, 2012-12-05 at 10:31 +0800, Yuanquan Chen wrote:
>>>>>>>>>
>>>>>>>>> On powerpc arch, some fixup work of PCI/PCI-e device is just done
>>>>>>>>> during the
>>>>>>>>> first scan at booting time. For the PCI/PCI-e device rescanned
>>>>>>>>> after
>>>>>>>>> linux OS
>>>>>>>>> booting up, the fixup work won't be done, which leads to
>>>>>>>>> dma_set_mask
>>>>>>>>> error or
>>>>>>>>> irq related issue in rescanned PCI/PCI-e device's driver. So, it
>>>>>>>>> does
>>>>>>>>> the same
>>>>>>>>> fixup work for the rescanned device to avoid this issue.
>>>>>>>>
>>>>>>>> Hrm, the patch is a bit gross. First the code shouldn't be
>>>>>>>> copy/pasted
>>>>>>>> that way but factored out.
>>>>>>
>>>>>> Please, at least format your email properly so I can try to undertand
>>>>>> without needing aspirin.
>>>>>>
>>>>>>> There's a judgement "if (!bus->is_added)" before calling of
>>>>>>> pcibios_fixup_bus in pci_scan_child_bus, so for the rescanned device,
>>>>>>> the fixup won't execute, which leads to fatal error in driver of
>>>>>>> rescanned
>>>>>>> device on freescale  powerpc, no this issues on x86 arch.
>>>>>>
>>>>>> First, none of that invalidates my statement that you shouldn't
>>>>>> duplicate a whole block of code like this. Even if your approach is
>>>>>> correct (which is debated separately), at the very least you should
>>>>>> factor the code out into a common function between the two copies.
>>>>>>
>>>>>>> Remove the judgement, let it to do the pcibios_fixup_bus
>>>>>>> directly, the error won't occur for the rescanned device. But it's
>>>>>>> general code, not proper to change here, so copy the
>>>>>>> pcibios_fixup_bus
>>>>>>> work to  pcibios_enable_device.
>>>>>>>
>>>>>>>> I'm surprised also that is_added is false when
>>>>>>>> pcibios_enable_device()
>>>>>>>> gets called ... that looks strange to me. At what point is that
>>>>>>>> enable
>>>>>>>> happening in the hotplug sequence ?
>>>>>>>
>>>>>>> All devices are rescanned and then call the pci_enable_devices and
>>>>>>> pci_bus_add_devices.
>>>>>>
>>>>>> Where ? How ? What is the sequence happening ? In any case, I think if
>>>>>> we need a proper fixup done per-device like that after scan we ought
>>>>>> to
>>>>>> create a new hook at the generic level rather than that sort of hack.
>>>>>>
>>>>> echo 1 > rescan to trigger dev_rescan_store:
>>>>>
>>>>> dev_rescan_store->pci_rescan_bus->pci_scan_child_bus,
>>>>> pci_assign_unassigned_bus_resources,
>>>>> pci_enable_bridges, pci_bus_add_devices
>>>>>
>>>>>
>>>>>
>>>>> pci_enable_bridges->pci_enable_device->__pci_enable_device_flags->do_pci_enable_device->
>>>>> pcibios_enable_device
>>>>>
>>>>> pci_bus_add_devices->pci_bus_add_device->"dev->is_added = 1"
>>>>>
>>>>> Yeah, it's general fixup code for every rescanned PCI/PCI-e device on
>>>>> powerpc at runtime. So if
>>>>> we want to call it in a ppc_md member, we need to wrap it as a function
>>>>> and
>>>>> assign it in every ppc_md,
>>>>> it isn't proper for the general code.
>>>>>
>>>>> Regards,
>>>>> yuanquan
>>>>>
>>>>>
>>>>>>> The patch code will be called by pci_enable_devices. The
>>>>>>> "dev->is_added"
>>>>>>> is set in pci_bus_add_device
>>>>>>> which is called by pci_bus_add_devices. So "dev->is_added" is false
>>>>>>> when
>>>>>>> checking it in pcibios_enable_device
>>>>>>> for the rescanned device.
>>>>>>
>>>>>> Who calls pci_enable_device() in the rescan case ? Why isn't it left
>>>>>> to
>>>>>> the driver ? I don't think we can rely on that behaviour not to
>>>>>> change.
>>>>>>
>>>>>>>> How do you trigger the rescan anyway ?
>>>>>>>
>>>>>>> Use the interface under /sys :
>>>>>>> echo 1 > /sys/bus/pci/devices/xxx/remove
>>>>>>>
>>>>>>> then echo 1 to the pci device which is the bus of the removed device
>>>>>>> echo 1 > /sys/bus/pci/devices/xxxx/rescan
>>>>>>> the removed device will be scanned and it's driver module will be
>>>>>>> loaded
>>>>>>> automatically.
>>>>>>
>>>>>> Yeah this code path are known to be fishy. I think the problem is at
>>>>>> the
>>>>>> generic abstraction level and that's where it needs to be fixed.
>>>>>>
>>>>>> Cheers,
>>>>>> Ben.
>>>>>>
>>>>>>> Regards,
>>>>>>> yuanquan
>>>>>>>>
>>>>>>>> I think the problem needs to be solve at a higher level, I'm adding
>>>>>>>> linux-pci & Bjorn to the CC list.
>>>>>>>>
>>>>>>>> Cheers,
>>>>>>>> Ben.
>>>>>>>>
>>>>>>>>> Signed-off-by: Yuanquan Chen <B41889@freescale.com>
>>>>>>>>> ---
>>>>>>>>>      arch/powerpc/kernel/pci-common.c |   20 ++++++++++++++++++++
>>>>>>>>>      1 file changed, 20 insertions(+)
>>>>>>>>>
>>>>>>>>> diff --git a/arch/powerpc/kernel/pci-common.c
>>>>>>>>> b/arch/powerpc/kernel/pci-common.c
>>>>>>>>> index 7f94f76..f0fb070 100644
>>>>>>>>> --- a/arch/powerpc/kernel/pci-common.c
>>>>>>>>> +++ b/arch/powerpc/kernel/pci-common.c
>>>>>>>>> @@ -1496,6 +1496,26 @@ int pcibios_enable_device(struct pci_dev
>>>>>>>>> *dev,
>>>>>>>>> int mask)
>>>>>>>>>                   if (ppc_md.pcibios_enable_device_hook(dev))
>>>>>>>>>                           return -EINVAL;
>>>>>>>>>      +    if (!dev->is_added) {
>>>>>>>>> +               /*
>>>>>>>>> +                * Fixup NUMA node as it may not be setup yet by
>>>>>>>>> the
>>>>>>>>> generic
>>>>>>>>> +                * code and is needed by the DMA init
>>>>>>>>> +                */
>>>>>>>>> +               set_dev_node(&dev->dev, pcibus_to_node(dev->bus));
>>>>>>>>> +
>>>>>>>>> +               /* Hook up default DMA ops */
>>>>>>>>> +               set_dma_ops(&dev->dev, pci_dma_ops);
>>>>>>>>> +               set_dma_offset(&dev->dev, PCI_DRAM_OFFSET);
>>>>>>>>> +
>>>>>>>>> +               /* Additional platform DMA/iommu setup */
>>>>>>>>> +               if (ppc_md.pci_dma_dev_setup)
>>>>>>>>> +                       ppc_md.pci_dma_dev_setup(dev);
>>>>>>>>> +
>>>>>>>>> +               /* Read default IRQs and fixup if necessary */
>>>>>>>>> +               pci_read_irq_line(dev);
>>>>>>>>> +               if (ppc_md.pci_irq_fixup)
>>>>>>>>> +                       ppc_md.pci_irq_fixup(dev);
>>>>>>>>> +       }
>>>>>>>>>           return pci_enable_resources(dev, mask);
>>>>>>>>>      }
>>>>
>>>> Is this the same issue Hiroo MATSUMOTO was working on earlier?
>>>> (http://comments.gmane.org/gmane.linux.ports.ppc.embedded/50080)
>>>
>>>
>>> Yeah, that's the exact problem I encountered. Please push it forward.
>>
>> Well, as I mentioned, there are unresolved issues, so it's not just a
>> matter of applying the most recent patch.  If you're interested in
>> this problem and have some hardware to test, you can help by looking
>> into some of the things I mentioned in the message at the URL below.
>
>
> Hi Helgaas , Matsumoto,
>
> Do you have new update about this issue? I will go on to investigate this
> issue in the next
> days.

No update from me.  If you can help resolve this, please do.

Bjorn

Patch

diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index 7f94f76..f0fb070 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -1496,6 +1496,26 @@  int pcibios_enable_device(struct pci_dev *dev, int mask)
 		if (ppc_md.pcibios_enable_device_hook(dev))
 			return -EINVAL;
 
+	if (!dev->is_added) {
+		/* 
+		 * Fixup NUMA node as it may not be setup yet by the generic
+		 * code and is needed by the DMA init
+		 */
+		set_dev_node(&dev->dev, pcibus_to_node(dev->bus));
+
+		/* Hook up default DMA ops */
+		set_dma_ops(&dev->dev, pci_dma_ops);
+		set_dma_offset(&dev->dev, PCI_DRAM_OFFSET);
+
+		/* Additional platform DMA/iommu setup */
+		if (ppc_md.pci_dma_dev_setup)
+			ppc_md.pci_dma_dev_setup(dev);
+
+		/* Read default IRQs and fixup if necessary */
+		pci_read_irq_line(dev);
+		if (ppc_md.pci_irq_fixup)
+			ppc_md.pci_irq_fixup(dev);
+	}
 	return pci_enable_resources(dev, mask);
 }