6.15-stable review patch. If anyone has any objections, please let me know.
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From: Melissa Wen mwen@igalia.com
commit 97a0f2b5f4d4afcec34376e4428e157ce95efa71 upstream.
In DCN401 pre-blending degamma LUT isn't affecting cursor as in previous DCN version. As this is not the behavior close to what is expected for CRTC degamma LUT, disable CRTC degamma LUT property in this HW.
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/4176 ---
When enabling HDR on KDE, it takes the first CRTC 1D LUT available and apply a color transformation (Gamma 2.2 -> PQ). AMD driver usually advertises a CRTC degamma LUT as the first CRTC 1D LUT, but it's actually applied pre-blending. In previous HW version, it seems to work fine because the 1D LUT was applied to cursor too, but DCN401 presents a different behavior and the 1D LUT isn't affecting the hardware cursor.
To address the wrong gamma on cursor with HDR (see the link), I came up with this patch that disables CRTC degamma LUT in this hw, since it presents a different behavior than others. With this KDE sees CRTC regamma LUT as the first post-blending 1D LUT available. This is actually more consistent with AMD color pipeline. It was tested by the reporter, since I don't have the HW available for local testing and debugging.
Melissa ---
Reviewed-by: Harry Wentland harry.wentland@amd.com Signed-off-by: Melissa Wen mwen@igalia.com Signed-off-by: Ivan Lipski ivan.lipski@amd.com Tested-by: Daniel Wheeler daniel.wheeler@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com (cherry picked from commit 340231cdceec2c45995d773a358ca3c341f151aa) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c @@ -737,7 +737,16 @@ int amdgpu_dm_crtc_init(struct amdgpu_di * support programmable degamma anywhere. */ is_dcn = dm->adev->dm.dc->caps.color.dpp.dcn_arch; - drm_crtc_enable_color_mgmt(&acrtc->base, is_dcn ? MAX_COLOR_LUT_ENTRIES : 0, + /* Dont't enable DRM CRTC degamma property for DCN401 since the + * pre-blending degamma LUT doesn't apply to cursor, and therefore + * can't work similar to a post-blending degamma LUT as in other hw + * versions. + * TODO: revisit it once KMS plane color API is merged. + */ + drm_crtc_enable_color_mgmt(&acrtc->base, + (is_dcn && + dm->adev->dm.dc->ctx->dce_version != DCN_VERSION_4_01) ? + MAX_COLOR_LUT_ENTRIES : 0, true, MAX_COLOR_LUT_ENTRIES);
drm_mode_crtc_set_gamma_size(&acrtc->base, MAX_COLOR_LEGACY_LUT_ENTRIES);