Re: [PATCH] drm/panel: rm68200: add backlight dependency
On Wed, Mar 14, 2018 at 09:49:54AM +0100, Arnd Bergmann wrote:
> On Wed, Mar 14, 2018 at 12:01 AM, Thierry Reding
> wrote:
> > On Tue, Mar 13, 2018 at 09:59:54PM +0100, Arnd Bergmann wrote:
> >> Like many other panel drivers, this one fails to build
> >> when backlight support is disabled:
> >>
> >> drivers/gpu/drm/panel/panel-raydium-rm68200.o: In function `rm68200_probe':
> >> panel-raydium-rm68200.c:(.text+0x14a): undefined reference to
> >> `devm_of_find_backlight'
> >>
> >> This adds the appropriate dependency.
> >>
> >> Fixes: 2b7ed18bed1a ("drm/panel: Add support for Raydium RM68200 panel
> >> driver")
> >> Signed-off-by: Arnd Bergmann
> >> ---
> >> drivers/gpu/drm/panel/Kconfig | 1 +
> >> 1 file changed, 1 insertion(+)
> >
> > This shouldn't be necessary. include/linux/backlight.h defines a stub if
> > the backlight class is not enabled.
> >
> > What tree are you seeing this on?
>
> This is on linux-next.
>
> It must be with BACKLIGHT_CLASS_DEVICE=m and
> DRM_PANEL_RAYDIUM_RM68200=y, meaning that it should
> be sufficient to do
>
> depends on BACKLIGHT_CLASS_DEVICE || BACKLIGHT_CLASS_DEVICE=n
>
> to force DRM_PANEL_RAYDIUM_RM68200 to be a loadable module
> whenever BACKLIGHT_CLASS_DEVICE=m. For the patch, I looked at
> what the other drivers in the same directory do and followed their
> example.
>
> I see three options here:
>
> 1. update my patch changelog with the explanation I wrote here but leave it
> untouched
> 2. use the more elaborate dependency (after testing) but not change the
> others
> 3. change all panel drivers with a backlight dependency the same way,
> possibly with a helper symbol like
>
> config BACKLIGHT_CLASS_DEVICE_OPTIONAL
> tristate
> default m if BACKLIGHT_CLASS_DEVICE=m
> default y
>
> Arnd
I went with option 1) and added some text that hopefully clarifies the
issue.
https://cgit.freedesktop.org/drm/drm-misc/commit/?id=a8efe516316472ac771ba3f591295c7515e46172
Thierry
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Re: [PATCH] drm/panel: rm68200: add backlight dependency
On Wed, Mar 14, 2018 at 12:01 AM, Thierry Reding
wrote:
> On Tue, Mar 13, 2018 at 09:59:54PM +0100, Arnd Bergmann wrote:
>> Like many other panel drivers, this one fails to build
>> when backlight support is disabled:
>>
>> drivers/gpu/drm/panel/panel-raydium-rm68200.o: In function `rm68200_probe':
>> panel-raydium-rm68200.c:(.text+0x14a): undefined reference to
>> `devm_of_find_backlight'
>>
>> This adds the appropriate dependency.
>>
>> Fixes: 2b7ed18bed1a ("drm/panel: Add support for Raydium RM68200 panel
>> driver")
>> Signed-off-by: Arnd Bergmann
>> ---
>> drivers/gpu/drm/panel/Kconfig | 1 +
>> 1 file changed, 1 insertion(+)
>
> This shouldn't be necessary. include/linux/backlight.h defines a stub if
> the backlight class is not enabled.
>
> What tree are you seeing this on?
This is on linux-next.
It must be with BACKLIGHT_CLASS_DEVICE=m and
DRM_PANEL_RAYDIUM_RM68200=y, meaning that it should
be sufficient to do
depends on BACKLIGHT_CLASS_DEVICE || BACKLIGHT_CLASS_DEVICE=n
to force DRM_PANEL_RAYDIUM_RM68200 to be a loadable module
whenever BACKLIGHT_CLASS_DEVICE=m. For the patch, I looked at
what the other drivers in the same directory do and followed their
example.
I see three options here:
1. update my patch changelog with the explanation I wrote here but leave it
untouched
2. use the more elaborate dependency (after testing) but not change the
others
3. change all panel drivers with a backlight dependency the same way,
possibly with a helper symbol like
config BACKLIGHT_CLASS_DEVICE_OPTIONAL
tristate
default m if BACKLIGHT_CLASS_DEVICE=m
default y
Arnd
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Re: [PATCH] drm/panel: rm68200: add backlight dependency
On Tue, Mar 13, 2018 at 09:59:54PM +0100, Arnd Bergmann wrote:
> Like many other panel drivers, this one fails to build
> when backlight support is disabled:
>
> drivers/gpu/drm/panel/panel-raydium-rm68200.o: In function `rm68200_probe':
> panel-raydium-rm68200.c:(.text+0x14a): undefined reference to
> `devm_of_find_backlight'
>
> This adds the appropriate dependency.
>
> Fixes: 2b7ed18bed1a ("drm/panel: Add support for Raydium RM68200 panel
> driver")
> Signed-off-by: Arnd Bergmann
> ---
> drivers/gpu/drm/panel/Kconfig | 1 +
> 1 file changed, 1 insertion(+)
This shouldn't be necessary. include/linux/backlight.h defines a stub if
the backlight class is not enabled.
What tree are you seeing this on?
Thierry
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