| Message ID | 20210709132600.5417-1-marex@denx.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | video: backlight: Drop maximum brightness override for brightness zero | expand |
Den 09.07.2021 15.26, skrev Marek Vasut: > The note in c2adda27d202f ("video: backlight: Add of_find_backlight helper > in backlight.c") says that gpio-backlight uses brightness as power state. > This has been fixed since in ec665b756e6f7 ("backlight: gpio-backlight: > Correct initial power state handling") and other backlight drivers do not > require this workaround. Drop the workaround. > > 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") I not sure about the rules, but if this is automatically picked up for stable, maybe this is needed to avoid changing behaviour on 4.19: Cc: <stable@vger.kernel.org> # 5.4+ of_find_backlight() was added in 4.17 and the gpio fix in 5.4. Or perhaps there are other ways to signal this dependency. > Signed-off-by: Marek Vasut <marex@denx.de> > Cc: Daniel Thompson <daniel.thompson@linaro.org> > Cc: Meghana Madhyastha <meghana.madhyastha@gmail.com> > Cc: Noralf Trønnes <noralf@tronnes.org> > Cc: Sean Paul <seanpaul@chromium.org> > Cc: Thierry Reding <treding@nvidia.com> > --- Acked-by: Noralf Trønnes <noralf@tronnes.org>
On Fri, Jul 09, 2021 at 03:53:16PM +0200, Noralf Trønnes wrote: > > > Den 09.07.2021 15.26, skrev Marek Vasut: > > The note in c2adda27d202f ("video: backlight: Add of_find_backlight helper > > in backlight.c") says that gpio-backlight uses brightness as power state. > > This has been fixed since in ec665b756e6f7 ("backlight: gpio-backlight: > > Correct initial power state handling") and other backlight drivers do not > > require this workaround. Drop the workaround. > > > > 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") > > I not sure about the rules, but if this is automatically picked up for > stable, maybe this is needed to avoid changing behaviour on 4.19: > > > of_find_backlight() was added in 4.17 and the gpio fix in 5.4. > > Or perhaps there are other ways to signal this dependency. Agree we need to make sure the Fixes: tag doesn't provoke regressions in v4.19. Is this the syntax appropriate? Cc: <stable@vger.kernel.org> # 5.4+ Cc: <stable@vger.kernel.org> # 4.19.x: ec665b756e6f7: backlight: gpio-backlight: Correct initial power state handling > > Signed-off-by: Marek Vasut <marex@denx.de> > > Cc: Daniel Thompson <daniel.thompson@linaro.org> > > Cc: Meghana Madhyastha <meghana.madhyastha@gmail.com> > > Cc: Noralf Trønnes <noralf@tronnes.org> > > Cc: Sean Paul <seanpaul@chromium.org> > > Cc: Thierry Reding <treding@nvidia.com> > > --- > > Acked-by: Noralf Trønnes <noralf@tronnes.org> With the above (or something similar to avoid problems with v4.19): Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Daniel.
diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c index 537fe1b376ad7..fc990e576340b 100644 --- a/drivers/video/backlight/backlight.c +++ b/drivers/video/backlight/backlight.c @@ -688,12 +688,6 @@ static struct backlight_device *of_find_backlight(struct device *dev) of_node_put(np); if (!bd) return ERR_PTR(-EPROBE_DEFER); - /* - * Note: gpio_backlight uses brightness as - * power state during probe - */ - if (!bd->props.brightness) - bd->props.brightness = bd->props.max_brightness; } }
The note in c2adda27d202f ("video: backlight: Add of_find_backlight helper in backlight.c") says that gpio-backlight uses brightness as power state. This has been fixed since in ec665b756e6f7 ("backlight: gpio-backlight: Correct initial power state handling") and other backlight drivers do not require this workaround. Drop the workaround. 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@denx.de> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: Meghana Madhyastha <meghana.madhyastha@gmail.com> Cc: Noralf Trønnes <noralf@tronnes.org> Cc: Sean Paul <seanpaul@chromium.org> Cc: Thierry Reding <treding@nvidia.com> --- drivers/video/backlight/backlight.c | 6 ------ 1 file changed, 6 deletions(-)