gpio: thunderx: select IRQ_DOMAIN_HIERARCHY instead of depends on

Message ID 1504662052-12478-1-git-send-email-yamada.masahiro@socionext.com
State Accepted
Commit 311de3ce96f453a5a6edb3066eb6109cc07e81d2
Headers show
Series
  • gpio: thunderx: select IRQ_DOMAIN_HIERARCHY instead of depends on
Related show

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(-)

-- 
2.7.4

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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?


-- 
Best Regards
Masahiro Yamada
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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)




-- 
Best Regards
Masahiro Yamada
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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