[PATCH v1 1/1] drm/drm_panel: Fix EXPORT of drm_panel_of_backlight() one more time

[Jani Nikula]

On Tue, 17 Dec 2019, Sam Ravnborg <sam at ravnborg.org> wrote:
> On Tue, Dec 17, 2019 at 08:25:03AM -0800, Randy Dunlap wrote:
>> On 12/17/19 6:07 AM, Andy Shevchenko wrote:
>> > The initial commit followed by the fix didn't take into consideration the case
>> > 
>> > CONFIG_DRM_PANEL=y
>> > CONFIG_BACKLIGHT_CLASS_DEVICE=m
>> > CONFIG_DRM_I915=y
>> > 
>> > where symbol devm_of_find_backlight() is not reachable from DRM subsystem.
>> > Quick fix is to avoid drm_panel_of_backlight() from exporting in such case.
>> > 
>> > Fixes: 907aa265fde6 ("drm/drm_panel: fix EXPORT of drm_panel_of_backlight")
>> > Reported-by: Randy Dunlap <rdunlap at infradead.org>
>> > Cc: Linus Walleij <linus.walleij at linaro.org>
>> > Cc: Sam Ravnborg <sam at ravnborg.org>
>> > Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>> > Cc: Thierry Reding <thierry.reding at gmail.com>
>> > Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>> > Cc: Sean Paul <sean at poorly.run>
>> > Cc: David Airlie <airlied at linux.ie>
>> > Cc: Daniel Vetter <daniel at ffwll.ch>
>> > Cc: Maxime Ripard <mripard at kernel.org>
>> > Cc: dri-devel at lists.freedesktop.org
>> > Signed-off-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
>> 
>> Yes, that fixes the build error.  Thanks.
>> 
>> Acked-by: Randy Dunlap <rdunlap at infradead.org> # build-tested
>
> Hi Andy - thanks for fixing this. And thanks Randy for verifying the
> fix.
> It passed my build test and is now pushed to drm-misc-next.

As I wrote in [1], this allows a configuration that builds and links,
but is silently broken. You won't get backlight support in drm panel
which would be a reasonable expectation with
CONFIG_BACKLIGHT_CLASS_DEVICE=m.

BR,
Jani.


[1] http://mid.mail-archive.com/87d0cnynst.fsf@intel.com

-- 
Jani Nikula, Intel Open Source Graphics Center