* [PATCH] drm/panel: rm68200: add backlight dependency
@ 2018-03-13 20:59 Arnd Bergmann
2018-03-13 23:01 ` Thierry Reding
0 siblings, 1 reply; 4+ messages in thread
From: Arnd Bergmann @ 2018-03-13 20:59 UTC (permalink / raw)
To: Thierry Reding, David Airlie
Cc: Arnd Bergmann, Philippe CORNU, Linus Walleij, dri-devel, linux-kernel
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 <arnd@arndb.de>
---
drivers/gpu/drm/panel/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index 077bc58c1913..25682ff3449a 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -112,6 +112,7 @@ config DRM_PANEL_RAYDIUM_RM68200
tristate "Raydium RM68200 720x1280 DSI video mode panel"
depends on OF
depends on DRM_MIPI_DSI
+ depends on BACKLIGHT_CLASS_DEVICE
help
Say Y here if you want to enable support for Raydium RM68200
720x1280 DSI video mode panel.
--
2.9.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] drm/panel: rm68200: add backlight dependency
2018-03-13 20:59 [PATCH] drm/panel: rm68200: add backlight dependency Arnd Bergmann
@ 2018-03-13 23:01 ` Thierry Reding
2018-03-14 8:49 ` Arnd Bergmann
0 siblings, 1 reply; 4+ messages in thread
From: Thierry Reding @ 2018-03-13 23:01 UTC (permalink / raw)
To: Arnd Bergmann
Cc: David Airlie, Philippe CORNU, Linus Walleij, dri-devel, linux-kernel
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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 <arnd@arndb.de>
> ---
> 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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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] drm/panel: rm68200: add backlight dependency
2018-03-13 23:01 ` Thierry Reding
@ 2018-03-14 8:49 ` Arnd Bergmann
2018-03-14 10:52 ` Thierry Reding
0 siblings, 1 reply; 4+ messages in thread
From: Arnd Bergmann @ 2018-03-14 8:49 UTC (permalink / raw)
To: Thierry Reding
Cc: David Airlie, Philippe CORNU, Linus Walleij, dri-devel,
Linux Kernel Mailing List
On Wed, Mar 14, 2018 at 12:01 AM, Thierry Reding
<thierry.reding@gmail.com> 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 <arnd@arndb.de>
>> ---
>> 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
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] drm/panel: rm68200: add backlight dependency
2018-03-14 8:49 ` Arnd Bergmann
@ 2018-03-14 10:52 ` Thierry Reding
0 siblings, 0 replies; 4+ messages in thread
From: Thierry Reding @ 2018-03-14 10:52 UTC (permalink / raw)
To: Arnd Bergmann
Cc: David Airlie, Philippe CORNU, Linus Walleij, dri-devel,
Linux Kernel Mailing List
[-- Attachment #1: Type: text/plain, Size: 2088 bytes --]
On Wed, Mar 14, 2018 at 09:49:54AM +0100, Arnd Bergmann wrote:
> On Wed, Mar 14, 2018 at 12:01 AM, Thierry Reding
> <thierry.reding@gmail.com> 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 <arnd@arndb.de>
> >> ---
> >> 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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2018-03-13 20:59 [PATCH] drm/panel: rm68200: add backlight dependency Arnd Bergmann
2018-03-13 23:01 ` Thierry Reding
2018-03-14 8:49 ` Arnd Bergmann
2018-03-14 10:52 ` Thierry Reding
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