From eaf56410ccb06f4af9475b7018ec46aa022ee99e Mon Sep 17 00:00:00 2001 From: Leo Li Date: Mon, 21 Oct 2019 14:58:47 -0400 Subject: [PATCH] drm/amdgpu: Add DC feature mask to disable fractional pwm MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit [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 Reviewed-by: Anthony Koo Tested-by: Lukáš Krejčí Signed-off-by: Alex Deucher --- 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 854d2caf18dd..620abe29ef08 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 8340ec0ab792..dc7eb28f0296 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, DC_PSR_MASK = 0x8, }; -- 2.45.2