gpio: thunderx: select IRQ_DOMAIN_HIERARCHY instead of depends on

Message ID 1504662052-12478-1-git-send-email-yamada.masahiro@socionext.com
State New
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Series
  • gpio: thunderx: select IRQ_DOMAIN_HIERARCHY instead of depends on
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Commit Message

Masahiro Yamada Sept. 6, 2017, 1:40 a.m.
IRQ_DOMAIN_HIERARCHY is not user-configurable, but supposed to be
selected by drivers that need IRQ domain hierarchy support.

GPIO_THUNDERX is the only user of "depends on IRQ_DOMAIN_HIERARCHY".
This means, we can not enable GPIO_THUNDERX unless other drivers
select IRQ_DOMAIN_HIERARCHY elsewhere.  This is odd.  Flip the logic.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

 drivers/gpio/Kconfig | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

David Daney Sept. 6, 2017, 2:09 a.m. | #1
On 09/05/2017 06:40 PM, Masahiro Yamada wrote:
> IRQ_DOMAIN_HIERARCHY is not user-configurable, but supposed to be
> selected by drivers that need IRQ domain hierarchy support.
> 
> GPIO_THUNDERX is the only user of "depends on IRQ_DOMAIN_HIERARCHY".
> This means, we can not enable GPIO_THUNDERX unless other drivers
> select IRQ_DOMAIN_HIERARCHY elsewhere.  This is odd.  Flip the logic.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

IRQ_DOMAIN_HIERARCHY is set as a result of ARCH_THUNDER (this SoC 
hardware), so it actually works as-is.  That said, this looks like a 
reasonable improvement, and will allow the COMPILE_TEST to enable it, so...

Acked-by: David Daney <david.daney@cavium.com>


> ---
> 
>   drivers/gpio/Kconfig | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 3388d54..3f80f16 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -453,7 +453,8 @@ config GPIO_TS4800
>   config GPIO_THUNDERX
>   	tristate "Cavium ThunderX/OCTEON-TX GPIO"
>   	depends on ARCH_THUNDER || (64BIT && COMPILE_TEST)
> -	depends on PCI_MSI && IRQ_DOMAIN_HIERARCHY
> +	depends on PCI_MSI
> +	select IRQ_DOMAIN_HIERARCHY
>   	select IRQ_FASTEOI_HIERARCHY_HANDLERS
>   	help
>   	  Say yes here to support the on-chip GPIO lines on the ThunderX
> 

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Masahiro Yamada Sept. 6, 2017, 4:20 a.m. | #2
Hi David,


2017-09-06 11:09 GMT+09:00 David Daney <ddaney@caviumnetworks.com>:
> On 09/05/2017 06:40 PM, Masahiro Yamada wrote:
>>
>> IRQ_DOMAIN_HIERARCHY is not user-configurable, but supposed to be
>> selected by drivers that need IRQ domain hierarchy support.
>>
>> GPIO_THUNDERX is the only user of "depends on IRQ_DOMAIN_HIERARCHY".
>> This means, we can not enable GPIO_THUNDERX unless other drivers
>> select IRQ_DOMAIN_HIERARCHY elsewhere.  This is odd.  Flip the logic.
>>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
>
>
> IRQ_DOMAIN_HIERARCHY is set as a result of ARCH_THUNDER (this SoC hardware),
> so it actually works as-is.


Right, ARCH_THUNDER does not select it directly,
but does it indirectly.  (this is not so clear...)

ARCH_THUNDER  -> ARM64 -> ARM_GIC -> IRQ_DOMAIN_HIERARCHY



>  That said, this looks like a reasonable
> improvement, and will allow the COMPILE_TEST to enable it, so...
>
> Acked-by: David Daney <david.daney@cavium.com>


BTW, I could not understand your intention of
(64BIT && COMPILE_TEST)

Why can COMPILE_TEST be enabled when 64BIT?
David Daney Sept. 6, 2017, 5:36 p.m. | #3
On 09/05/2017 09:20 PM, Masahiro Yamada wrote:
> Hi David,
> 
> 
> 2017-09-06 11:09 GMT+09:00 David Daney <ddaney@caviumnetworks.com>:
>> On 09/05/2017 06:40 PM, Masahiro Yamada wrote:
>>>
>>> IRQ_DOMAIN_HIERARCHY is not user-configurable, but supposed to be
>>> selected by drivers that need IRQ domain hierarchy support.
>>>
>>> GPIO_THUNDERX is the only user of "depends on IRQ_DOMAIN_HIERARCHY".
>>> This means, we can not enable GPIO_THUNDERX unless other drivers
>>> select IRQ_DOMAIN_HIERARCHY elsewhere.  This is odd.  Flip the logic.
>>>
>>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
>>
>>
>> IRQ_DOMAIN_HIERARCHY is set as a result of ARCH_THUNDER (this SoC hardware),
>> so it actually works as-is.
> 
> 
> Right, ARCH_THUNDER does not select it directly,
> but does it indirectly.  (this is not so clear...)
> 
> ARCH_THUNDER  -> ARM64 -> ARM_GIC -> IRQ_DOMAIN_HIERARCHY
> 
> 
> 
>>   That said, this looks like a reasonable
>> improvement, and will allow the COMPILE_TEST to enable it, so...
>>
>> Acked-by: David Daney <david.daney@cavium.com>
> 
> 
> BTW, I could not understand your intention of
> (64BIT && COMPILE_TEST)
> 

The driver uses readq()/writeq(), which are not available in some 32BIT 
kernels.  So to ensure that it can build without error we depend on 
64BIT as a proxy for the availability of readq()/writeq()


David
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Masahiro Yamada Sept. 7, 2017, 1:03 a.m. | #4
Hi David,


2017-09-07 2:36 GMT+09:00 David Daney <ddaney@caviumnetworks.com>:
> On 09/05/2017 09:20 PM, Masahiro Yamada wrote:
>>
>> Hi David,
>>
>>
>> 2017-09-06 11:09 GMT+09:00 David Daney <ddaney@caviumnetworks.com>:
>>>
>>> On 09/05/2017 06:40 PM, Masahiro Yamada wrote:
>>>>
>>>>
>>>> IRQ_DOMAIN_HIERARCHY is not user-configurable, but supposed to be
>>>> selected by drivers that need IRQ domain hierarchy support.
>>>>
>>>> GPIO_THUNDERX is the only user of "depends on IRQ_DOMAIN_HIERARCHY".
>>>> This means, we can not enable GPIO_THUNDERX unless other drivers
>>>> select IRQ_DOMAIN_HIERARCHY elsewhere.  This is odd.  Flip the logic.
>>>>
>>>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
>>>
>>>
>>>
>>> IRQ_DOMAIN_HIERARCHY is set as a result of ARCH_THUNDER (this SoC
>>> hardware),
>>> so it actually works as-is.
>>
>>
>>
>> Right, ARCH_THUNDER does not select it directly,
>> but does it indirectly.  (this is not so clear...)
>>
>> ARCH_THUNDER  -> ARM64 -> ARM_GIC -> IRQ_DOMAIN_HIERARCHY
>>
>>
>>
>>>   That said, this looks like a reasonable
>>> improvement, and will allow the COMPILE_TEST to enable it, so...
>>>
>>> Acked-by: David Daney <david.daney@cavium.com>
>>
>>
>>
>> BTW, I could not understand your intention of
>> (64BIT && COMPILE_TEST)
>>
>
> The driver uses readq()/writeq(), which are not available in some 32BIT
> kernels.  So to ensure that it can build without error we depend on 64BIT as
> a proxy for the availability of readq()/writeq()
>
>


IMHO, drivers code should not depend on CPU architecture too much.


Does the following make sense for your driver?


- split {read,write}q into two transactions of {read,write}l

or

- include <linux/io-64-nonatomic-hi-lo.h> or
          <linux-io-64-nonatomic-lo-hi.h>
   (choose a suitable one for your driver)
David Daney Sept. 7, 2017, 1:18 a.m. | #5
On 09/06/2017 06:03 PM, Masahiro Yamada wrote:
> Hi David,
> 
> 
> 2017-09-07 2:36 GMT+09:00 David Daney <ddaney@caviumnetworks.com>:
>> On 09/05/2017 09:20 PM, Masahiro Yamada wrote:
>>>
>>> Hi David,
>>>
>>>
>>> 2017-09-06 11:09 GMT+09:00 David Daney <ddaney@caviumnetworks.com>:
>>>>
>>>> On 09/05/2017 06:40 PM, Masahiro Yamada wrote:
>>>>>
>>>>>
>>>>> IRQ_DOMAIN_HIERARCHY is not user-configurable, but supposed to be
>>>>> selected by drivers that need IRQ domain hierarchy support.
>>>>>
>>>>> GPIO_THUNDERX is the only user of "depends on IRQ_DOMAIN_HIERARCHY".
>>>>> This means, we can not enable GPIO_THUNDERX unless other drivers
>>>>> select IRQ_DOMAIN_HIERARCHY elsewhere.  This is odd.  Flip the logic.
>>>>>
>>>>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
>>>>
>>>>
>>>>
>>>> IRQ_DOMAIN_HIERARCHY is set as a result of ARCH_THUNDER (this SoC
>>>> hardware),
>>>> so it actually works as-is.
>>>
>>>
>>>
>>> Right, ARCH_THUNDER does not select it directly,
>>> but does it indirectly.  (this is not so clear...)
>>>
>>> ARCH_THUNDER  -> ARM64 -> ARM_GIC -> IRQ_DOMAIN_HIERARCHY
>>>
>>>
>>>
>>>>    That said, this looks like a reasonable
>>>> improvement, and will allow the COMPILE_TEST to enable it, so...
>>>>
>>>> Acked-by: David Daney <david.daney@cavium.com>
>>>
>>>
>>>
>>> BTW, I could not understand your intention of
>>> (64BIT && COMPILE_TEST)
>>>
>>
>> The driver uses readq()/writeq(), which are not available in some 32BIT
>> kernels.  So to ensure that it can build without error we depend on 64BIT as
>> a proxy for the availability of readq()/writeq()
>>
>>
> 
> 
> IMHO, drivers code should not depend on CPU architecture too much.
> 

The CPU and the device are in a SoC (both on the same silicon die), 
there is no way they can be used apart from one another.


> 
> Does the following make sense for your driver?
> 
> 
> - split {read,write}q into two transactions of {read,write}l

No.  The registers must be accessed with 64-bit operations.

We are not going to screw around complicating the driver so that it can 
work on hypothetical non-existent systems.

If we ever put this GPIO hardware unit in a system with a 32-bit CPU, we 
will at that time, and only then, modify it to work with 32-bit operations.

> 
> or
> 
> - include <linux/io-64-nonatomic-hi-lo.h> or
>            <linux-io-64-nonatomic-lo-hi.h>
>     (choose a suitable one for your driver)
> 
> 
> 
> 

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Linus Walleij Sept. 12, 2017, 9:24 a.m. | #6
On Wed, Sep 6, 2017 at 3:40 AM, Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:

> IRQ_DOMAIN_HIERARCHY is not user-configurable, but supposed to be
> selected by drivers that need IRQ domain hierarchy support.
>
> GPIO_THUNDERX is the only user of "depends on IRQ_DOMAIN_HIERARCHY".
> This means, we can not enable GPIO_THUNDERX unless other drivers
> select IRQ_DOMAIN_HIERARCHY elsewhere.  This is odd.  Flip the logic.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Patch applied with David's ACK.

Yours,
Linus Walleij
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Patch

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 3388d54..3f80f16 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -453,7 +453,8 @@  config GPIO_TS4800
 config GPIO_THUNDERX
 	tristate "Cavium ThunderX/OCTEON-TX GPIO"
 	depends on ARCH_THUNDER || (64BIT && COMPILE_TEST)
-	depends on PCI_MSI && IRQ_DOMAIN_HIERARCHY
+	depends on PCI_MSI
+	select IRQ_DOMAIN_HIERARCHY
 	select IRQ_FASTEOI_HIERARCHY_HANDLERS
 	help
 	  Say yes here to support the on-chip GPIO lines on the ThunderX