We've seen similar problems internally. Michael, does this "fix" your issue? Anthony, looks like smooth_brightness is problematic on (some) renoir systems. Thoughts? Thanks, Harry On 2020-05-20 5:47 p.m., Alex Deucher wrote: > Adding some display people. > > On Wed, May 20, 2020 at 5:46 PM Alexander Monakov <amonakov@xxxxxxxxx> wrote: >> >> Hello, >> >> 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. >> >> Alexander >> >> 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) >> dmcu_set_backlight_level(abm_dce, >> backlight_pwm_u16_16, >> frame_ramp, >> _______________________________________________ >> amd-gfx mailing list >> amd-gfx@xxxxxxxxxxxxxxxxxxxxx >> https://lists.freedesktop.org/mailman/listinfo/amd-gfx _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
