[RFC,PATCHv3,3/4] x86/pci: Initial commit for new VMD device driver

On 2015/11/4 23:14, Thomas Gleixner wrote:
> On Wed, 4 Nov 2015, Keith Busch wrote:
> 
>> On Tue, Nov 03, 2015 at 12:42:02PM +0100, Thomas Gleixner wrote:
>>> On Tue, 3 Nov 2015, Keith Busch wrote:
>>>>>> +	msi_irqdomain = pci_msi_create_irq_domain(NULL, &pci_chained_msi_domain_info,
>>>>>> +						  vmd_irqdomain);
>>>
>>> But that parent limitation does not matter simply because your
>>> msi_irqdomain does not follow down the hierarchy in the allocation
>>> path.
>>>
>>> So we can avoid the vmd_irqdomain creation completely. It's just
>>> wasting memory and has no value at all. Creating the msi domain with a
>>> NULL parent is possible.
>>
>> I'm having trouble following the hierarchy and didn't understand the
>> connection between the parent and msi comain. It's still new to me,
>> but I don't think a NULL parent is allowable with msi domains:
>>
>>  pci_msi_setup_msi_irqs()
>>   pci_msi_domain_alloc_irqs()
>>    msi_domain_alloc_irqs()
>>     __irq_domain_alloc_irqs()
>>      irq_domain_alloc_irqs_recursive()
>>       msi_domain_alloc()
>>        irq_domain_alloc_irqs_parent()
>>
>> The last call returns -ENOSYS since there parent is NULL. Was the
>> intension to allow no parent, or do I still need to allocate one to
>> achieve the desired chaining?
> 
> Hmm, seems I missed that part. But that's a fixable problem. Jiang?
Hi Keith,
	Could you please try the attached patch?
Thanks!
Gerry

> 
> Thanks,
> 
> 	tglx
>  
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On Thu, Nov 05, 2015 at 02:35:31PM +0800, Jiang Liu wrote:
> Hi Keith,
> 	Could you please try the attached patch?
> Thanks!
> Gerry

Thanks! I anticipated this and tested the same thing yesterday, and it
is successful.

I'll apply to the series and send a new revision hopefully today. Not
requiring a parent simplifies the driver since we don't define
irq_domain_ops now, and the functionality they provided moves to the
irq_chip.



> From: Liu Jiang <jiang.liu@linux.intel.com>
> Date: Thu, 5 Nov 2015 11:25:07 +0800
> Subject: [PATCH] msi: Relax msi_domain_alloc() to support parentless MSI
>  irqdomains
> 
> Previously msi_domain_alloc() assumes MSI irqdomains always have parent
> irqdomains, but that's not true for the new Intel VMD devices. So relax
> msi_domain_alloc() to support parentless MSI irqdomains.
> 
> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
> Signed-off-by: Liu Jiang <jiang.liu@linux.intel.com>
> ---
>  kernel/irq/msi.c |    8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
> index 7e6512b9dc1f..e4d3d707efff 100644
> --- a/kernel/irq/msi.c
> +++ b/kernel/irq/msi.c
> @@ -109,9 +109,11 @@ static int msi_domain_alloc(struct irq_domain *domain, unsigned int virq,
>  	if (irq_find_mapping(domain, hwirq) > 0)
>  		return -EEXIST;
>  
> -	ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, arg);
> -	if (ret < 0)
> -		return ret;
> +	if (domain->parent) {
> +		ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, arg);
> +		if (ret < 0)
> +			return ret;
> +	}
>  
>  	for (i = 0; i < nr_irqs; i++) {
>  		ret = ops->msi_init(domain, info, virq + i, hwirq + i, arg);
> -- 
> 1.7.10.4
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