On 7/9/21 1:03 PM, Daniel Thompson wrote:
On Thu, Jul 08, 2021 at 11:10:58AM +0200, Marek Vasut wrote:The note in c2adda27d202f ("video: backlight: Add of_find_backlight helper in backlight.c") says that gpio-backlight uses brightness as power state. Other backlight drivers do not, so limit this workaround to gpio-backlight. This fixes the case where e.g. pwm-backlight can perfectly well be set to brightness 0 on boot in DT, which without this patch leads to the display brightness to be max instead of off. Fixes: c2adda27d202f ("video: backlight: Add of_find_backlight helper in backlight.c") Signed-off-by: Marek Vasut <marex@xxxxxxx> Cc: Daniel Thompson <daniel.thompson@xxxxxxxxxx> Cc: Meghana Madhyastha <meghana.madhyastha@xxxxxxxxx> Cc: Noralf Trønnes <noralf@xxxxxxxxxxx> Cc: Sean Paul <seanpaul@xxxxxxxxxxxx> Cc: Thierry Reding <treding@xxxxxxxxxx>I have to admit that this patch really does makes it clear just how nasty the hack in of_find_backlight() currently is. Moreover I think it is also be obsolete. gpio-backlight power mode handling was pretty broken when this code was introduced. It was fixed in 2019 by ec665b756e6f ("backlight: gpio backlight: Correct initial power state handling") by trying to match the behaviour of PWM backlight. The new code always sets the brightness to 1 so I think we can just remove the hack from of_find_backlight() since I think it is unreachable.
I assume by "new code" you mean the fixed gpio-backlight driver ? Dropping the whole code after the Note: is fine by me.
