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drm/amd/display: disable SubVP + DRR to prevent underflow

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[Why&How]
Temporarily disable SubVP+DRR since Xorg has an architectural limitation
where freesync will not work in a multi monitor configuration. SubVP+DRR
requires that freesync be working.

Whether OS has variable refresh setting enabled or not, the state on
the crtc remains same unless an application requests VRR. Due to this,
there is no way to know whether freesync will actually work or not
while we are on the desktop from the kernel's perspective.

If userspace does not have a limitation with multi-display freesync (for
example wayland), then this feature can be enabled by adding a
dcfeaturemask option to amdgpu on the kernel cmdline like:

amdgpu.dcfeaturemask=0x200

Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Aurabindo Pillai
2023-02-15 12:51:20 -05:00
committed by Alex Deucher
parent ac0bb08d2c
commit 80c6d6804f
4 changed files with 11 additions and 1 deletions
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5
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
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@@ -1604,6 +1604,11 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
if (amdgpu_dc_feature_mask & DC_DISABLE_LTTPR_DP2_0)
init_data.flags.allow_lttpr_non_transparent_mode.bits.DP2_0 = true;
/* Disable SubVP + DRR config by default */
init_data.flags.disable_subvp_drr = true;
if (amdgpu_dc_feature_mask & DC_ENABLE_SUBVP_DRR)
init_data.flags.disable_subvp_drr = false;
init_data.flags.seamless_boot_edp_requested = false;
if (check_seamless_boot_capability(adev)) {