From: Leo Li <sunpeng...@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
Signed-off-by: Leo Li <sunpeng...@amd.com>
---
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;
--
2.23.0
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