[PATCH] drm/tegra: mark t186 display hub PM functions __maybe_unused

[PATCH] drm/tegra: mark t186 display hub PM functions __maybe_unused

[Arnd Bergmann]

The newly introduced driver has optional suspend/resume functions,
causing a warning when CONFIG_PM is disabled:

drivers/gpu/drm/tegra/hub.c:749:12: error: 'tegra_display_hub_resume' defined but not used [-Werror=unused-function]
drivers/gpu/drm/tegra/hub.c:733:12: error: 'tegra_display_hub_suspend' defined but not used [-Werror=unused-function]

This marks them __maybe_unused to shut up the warnings.

Fixes: c4755fb9064f ("drm/tegra: Add Tegra186 display hub support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/gpu/drm/tegra/hub.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tegra/hub.c b/drivers/gpu/drm/tegra/hub.c
index cccd44711d68..f4911feda9ff 100644
--- a/drivers/gpu/drm/tegra/hub.c
+++ b/drivers/gpu/drm/tegra/hub.c
@@ -730,7 +730,7 @@ static int tegra_display_hub_remove(struct platform_device *pdev)
 	return err;
 }
 
-static int tegra_display_hub_suspend(struct device *dev)
+static int __maybe_unused tegra_display_hub_suspend(struct device *dev)
 {
 	struct tegra_display_hub *hub = dev_get_drvdata(dev);
 	int err;
@@ -746,7 +746,7 @@ static int tegra_display_hub_suspend(struct device *dev)
 	return 0;
 }
 
-static int tegra_display_hub_resume(struct device *dev)
+static int __maybe_unused tegra_display_hub_resume(struct device *dev)
 {
 	struct tegra_display_hub *hub = dev_get_drvdata(dev);
 	int err;
-- 
2.9.0

Re: [PATCH] drm/tegra: mark t186 display hub PM functions __maybe_unused

[Dmitry Osipenko]

On 15.12.2017 15:51, Arnd Bergmann wrote:
> The newly introduced driver has optional suspend/resume functions,
> causing a warning when CONFIG_PM is disabled:
> 
> drivers/gpu/drm/tegra/hub.c:749:12: error: 'tegra_display_hub_resume' defined but not used [-Werror=unused-function]
> drivers/gpu/drm/tegra/hub.c:733:12: error: 'tegra_display_hub_suspend' defined but not used [-Werror=unused-function]
> 
> This marks them __maybe_unused to shut up the warnings.
> 
> Fixes: c4755fb9064f ("drm/tegra: Add Tegra186 display hub support")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/gpu/drm/tegra/hub.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/tegra/hub.c b/drivers/gpu/drm/tegra/hub.c
> index cccd44711d68..f4911feda9ff 100644
> --- a/drivers/gpu/drm/tegra/hub.c
> +++ b/drivers/gpu/drm/tegra/hub.c
> @@ -730,7 +730,7 @@ static int tegra_display_hub_remove(struct platform_device *pdev)
>  	return err;
>  }
>  
> -static int tegra_display_hub_suspend(struct device *dev)
> +static int __maybe_unused tegra_display_hub_suspend(struct device *dev)
>  {
>  	struct tegra_display_hub *hub = dev_get_drvdata(dev);
>  	int err;
> @@ -746,7 +746,7 @@ static int tegra_display_hub_suspend(struct device *dev)
>  	return 0;
>  }
>  
> -static int tegra_display_hub_resume(struct device *dev)
> +static int __maybe_unused tegra_display_hub_resume(struct device *dev)
>  {
>  	struct tegra_display_hub *hub = dev_get_drvdata(dev);
>  	int err;
> 

Probably would be better to put '#ifdef CONFIG_PM' around these functions for
the consistency with the other drm/tegra files.

Re: [PATCH] drm/tegra: mark t186 display hub PM functions __maybe_unused

[Arnd Bergmann]

On Fri, Dec 15, 2017 at 2:10 PM, Dmitry Osipenko <digetx@gmail.com> wrote:
> On 15.12.2017 15:51, Arnd Bergmann wrote:
>> --- a/drivers/gpu/drm/tegra/hub.c
>> +++ b/drivers/gpu/drm/tegra/hub.c
>> @@ -730,7 +730,7 @@ static int tegra_display_hub_remove(struct platform_device *pdev)
>>       return err;
>>  }
>>
>> -static int tegra_display_hub_suspend(struct device *dev)
>> +static int __maybe_unused tegra_display_hub_suspend(struct device *dev)
>>  {
>>       struct tegra_display_hub *hub = dev_get_drvdata(dev);
>>       int err;
>> @@ -746,7 +746,7 @@ static int tegra_display_hub_suspend(struct device *dev)
>>       return 0;
>>  }
>>
>> -static int tegra_display_hub_resume(struct device *dev)
>> +static int __maybe_unused tegra_display_hub_resume(struct device *dev)
>>  {
>>       struct tegra_display_hub *hub = dev_get_drvdata(dev);
>>       int err;
>>
>
> Probably would be better to put '#ifdef CONFIG_PM' around these functions for
> the consistency with the other drm/tegra files.

I usually use __maybe_unused because it is less error-prone, the
#ifdefs are often
wrong, either they are around the wrong functions or they use CONFIG_PM
CONFIG_PM_SLEEP interchangeably, which they are not. If you want to
add a patch with the correct #ifdef instead of my patch, that's fine with me
(add a Reported-by tag then), but I won't send a patch to do that myself.

        Arnd

Re: [PATCH] drm/tegra: mark t186 display hub PM functions __maybe_unused

[Thierry Reding]

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On Fri, Dec 15, 2017 at 01:51:52PM +0100, Arnd Bergmann wrote:
> The newly introduced driver has optional suspend/resume functions,
> causing a warning when CONFIG_PM is disabled:
> 
> drivers/gpu/drm/tegra/hub.c:749:12: error: 'tegra_display_hub_resume' defined but not used [-Werror=unused-function]
> drivers/gpu/drm/tegra/hub.c:733:12: error: 'tegra_display_hub_suspend' defined but not used [-Werror=unused-function]
> 
> This marks them __maybe_unused to shut up the warnings.
> 
> Fixes: c4755fb9064f ("drm/tegra: Add Tegra186 display hub support")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/gpu/drm/tegra/hub.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

We had touched on this topic in a different thread. The Tegra DRM driver
currently relies on runtime PM to work properly. I don't see a reason to
not make that official by adding a select PM to menuconfig ARCH_TEGRA on
32-bit ARM just like we already do on 64-bit ARM.

I've gone and applied this patch as an interim solution. Once we've made
the switch to select PM on all generations of Tegra we can remove all
the #ifdef and __maybe_unused.

Thanks,
Thierry

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Re: [PATCH] drm/tegra: mark t186 display hub PM functions __maybe_unused

[Arnd Bergmann]

On Fri, Dec 15, 2017 at 2:33 PM, Thierry Reding
<thierry.reding@gmail.com> wrote:
> On Fri, Dec 15, 2017 at 01:51:52PM +0100, Arnd Bergmann wrote:
>> The newly introduced driver has optional suspend/resume functions,
>> causing a warning when CONFIG_PM is disabled:
>>
>> drivers/gpu/drm/tegra/hub.c:749:12: error: 'tegra_display_hub_resume' defined but not used [-Werror=unused-function]
>> drivers/gpu/drm/tegra/hub.c:733:12: error: 'tegra_display_hub_suspend' defined but not used [-Werror=unused-function]
>>
>> This marks them __maybe_unused to shut up the warnings.
>>
>> Fixes: c4755fb9064f ("drm/tegra: Add Tegra186 display hub support")
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>> ---
>>  drivers/gpu/drm/tegra/hub.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> We had touched on this topic in a different thread. The Tegra DRM driver
> currently relies on runtime PM to work properly. I don't see a reason to
> not make that official by adding a select PM to menuconfig ARCH_TEGRA on
> 32-bit ARM just like we already do on 64-bit ARM.
>
> I've gone and applied this patch as an interim solution. Once we've made
> the switch to select PM on all generations of Tegra we can remove all
> the #ifdef and __maybe_unused.

Sounds good, thanks!

       Arnd

Re: [PATCH] drm/tegra: mark t186 display hub PM functions __maybe_unused

[Dmitry Osipenko]

On 15.12.2017 16:33, Thierry Reding wrote:
> On Fri, Dec 15, 2017 at 01:51:52PM +0100, Arnd Bergmann wrote:
>> The newly introduced driver has optional suspend/resume functions,
>> causing a warning when CONFIG_PM is disabled:
>>
>> drivers/gpu/drm/tegra/hub.c:749:12: error: 'tegra_display_hub_resume' defined but not used [-Werror=unused-function]
>> drivers/gpu/drm/tegra/hub.c:733:12: error: 'tegra_display_hub_suspend' defined but not used [-Werror=unused-function]
>>
>> This marks them __maybe_unused to shut up the warnings.
>>
>> Fixes: c4755fb9064f ("drm/tegra: Add Tegra186 display hub support")
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>> ---
>>  drivers/gpu/drm/tegra/hub.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> We had touched on this topic in a different thread. The Tegra DRM driver
> currently relies on runtime PM to work properly. I don't see a reason to
> not make that official by adding a select PM to menuconfig ARCH_TEGRA on
> 32-bit ARM just like we already do on 64-bit ARM.

Since you've repeated the third time that you 'don't see a reason', I'll take it
as NAK for my patch that made drm/tegra to work with the disabled PM and drop
it. Next time please state it clearly if you oppose to something strongly. Thanks.