From: Leo Li sunpeng.li@amd.com
[Why]
Some LED panel drivers might not like fractional PWM. In such cases, backlight flickering may be observed.
[How]
Add a DC feature mask to disable fractional PWM, and associate it with the preexisting dc_config flag.
The flag is only plumbed through the dmcu firmware, so plumb it through the driver path as well.
To disable, add the following to the linux cmdline: amdgpu.dcfeaturemask=0x4
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=204957 Signed-off-by: Leo Li sunpeng.li@amd.com ---
v2: Add bugzilla link
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 3 +++ drivers/gpu/drm/amd/display/dc/dce/dce_abm.c | 4 ++++ drivers/gpu/drm/amd/include/amd_shared.h | 1 + 3 files changed, 8 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c index 1cf4beb76835..73f917d4d1e1 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -728,6 +728,9 @@ static int amdgpu_dm_init(struct amdgpu_device *adev) if (amdgpu_dc_feature_mask & DC_MULTI_MON_PP_MCLK_SWITCH_MASK) init_data.flags.multi_mon_pp_mclk_switch = true;
+ if (amdgpu_dc_feature_mask & DC_DISABLE_FRACTIONAL_PWM_MASK) + init_data.flags.disable_fractional_pwm = true; + init_data.flags.power_down_display_on_boot = true;
#ifdef CONFIG_DRM_AMD_DC_DCN2_0 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 d759fdca7fdb..b8a3fc505c9b 100644 --- a/drivers/gpu/drm/amd/display/dc/dce/dce_abm.c +++ b/drivers/gpu/drm/amd/display/dc/dce/dce_abm.c @@ -404,6 +404,10 @@ static bool dce_abm_init_backlight(struct abm *abm) /* Enable the backlight output */ REG_UPDATE(BL_PWM_CNTL, BL_PWM_EN, 1);
+ /* Disable fractional pwm if configured */ + REG_UPDATE(BL_PWM_CNTL, BL_PWM_FRACTIONAL_EN, + abm->ctx->dc->config.disable_fractional_pwm ? 0 : 1); + /* Unlock group 2 backlight registers */ REG_UPDATE(BL_PWM_GRP1_REG_LOCK, BL_PWM_GRP1_REG_LOCK, 0); diff --git a/drivers/gpu/drm/amd/include/amd_shared.h b/drivers/gpu/drm/amd/include/amd_shared.h index 8889aaceec60..5450ed762b7a 100644 --- a/drivers/gpu/drm/amd/include/amd_shared.h +++ b/drivers/gpu/drm/amd/include/amd_shared.h @@ -143,6 +143,7 @@ enum PP_FEATURE_MASK { enum DC_FEATURE_MASK { DC_FBC_MASK = 0x1, DC_MULTI_MON_PP_MCLK_SWITCH_MASK = 0x2, + DC_DISABLE_FRACTIONAL_PWM_MASK = 0x4, };
enum amd_dpm_forced_level;