Flaky brightness on Renoir
alexdeucher at gmail.com
Wed May 20 21:47:44 UTC 2020
Adding some display people.
On Wed, May 20, 2020 at 5:46 PM Alexander Monakov <amonakov at ispras.ru> wrote:
> I have a laptop with the recent Renoir SoC. Screen brightness is
> controlled via the amdgpu driver. Unfortunately it doesn't work
> properly: brightness doesn't go below a certain threshold. In one
> experiment I've found the threshold to be about 95 (of 255), which is
> quite high.
> There's a bugreport on the tracker from a person with the same laptop
> model as mine that says that the threshold may vary from boot to boot.
> So far I was able to find a workaround: avoiding
> dmcu_set_backlight_level like in the patch below gives more reliable
> backlight control (but at the expense of breaking "actual_brightness"
> sysfs file, because it reads from DMCU registers).
> What might be the problem and can I help investigate this further? Would
> really like to see this work properly.
> diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_abm.c b/drivers/gpu/drm/amd/display/dc/dce/dce_abm.c
> index b8a3fc505c9b..3274b0d15893 100644
> --- a/drivers/gpu/drm/amd/display/dc/dce/dce_abm.c
> +++ b/drivers/gpu/drm/amd/display/dc/dce/dce_abm.c
> @@ -428,7 +428,7 @@ static bool dce_abm_set_backlight_level_pwm(
> backlight_pwm_u16_16, backlight_pwm_u16_16);
> /* If DMCU is in reset state, DMCU is uninitialized */
> - if (use_smooth_brightness)
> + if (0 && use_smooth_brightness)
> amd-gfx mailing list
> amd-gfx at lists.freedesktop.org
More information about the amd-gfx