| Message ID | 20180313210015.3344380-1-arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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
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
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
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.
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(+)