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drm/amdgpu: Add DC feature mask to disable fractional pwm

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[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>
Reviewed-by: Anthony Koo <anthony.koo@amd.com>
Tested-by: Lukáš Krejčí <lskrejci@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Leo Li
2019-10-21 14:58:47 -04:00
committed by Alex Deucher
parent 9f0256da6b
commit eaf56410cc
3 changed files with 8 additions and 0 deletions
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3
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
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@@ -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