From: Fangzhi Zuo Jerry.Zuo@amd.com

Before enabling new crtc, stream_count in dc_state does not sync with that in drm_atomic_state. Validating dsc in such case would leave newly added stream not jointly participating in dsc optimization with existing streams, but simply using default initialized vcpi all the time which gives wrong dsc determination decision.

Consider the scenaio where one 4k60 connected to the dock under dp-alt mode. Since dp-alt mode is 2-lane setup, stream 1 consumes 63 slots with dsc needed. Then hook up a second 4k60 to the dock. stream 2 connected with 65 slot initialized by default without dsc. dsc pre validate will not jointly optimize stream 2 with stream 1 before crtc 2 added into the dc_state. That leads to stream 2 not getting dsc optimization, and trigger atomic_check failure all the time, as 65 > 63 limit.

After getting all new crtcs added into the state, stream_count in dc_state correctly reflect that in drm_atomic_state which comes up with correct dsc decision.

Fixes: 71be4b16d39a ("drm/amd/display: dsc validate fail not pass to atomic check") Reviewed-by: Roman Li Roman.Li@amd.com Acked-by: Qingqing Zhuo qingqing.zhuo@amd.com Signed-off-by: Fangzhi Zuo Jerry.Zuo@amd.com Tested-by: Mark Broadworth mark.broadworth@amd.com Cc: stable@vger.kernel.org --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)

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 17c3daac837a..63f076a46260 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -9408,10 +9408,6 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev, } } } - if (!pre_validate_dsc(state, &dm_state, vars)) { - ret = -EINVAL; - goto fail; - } } #endif for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) { @@ -9545,6 +9541,15 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev, } }

+#if defined(CONFIG_DRM_AMD_DC_DCN) + if (dc_resource_is_dsc_encoding_supported(dc)) { + if (!pre_validate_dsc(state, &dm_state, vars)) { + ret = -EINVAL; + goto fail; + } + } +#endif + /* Run this here since we want to validate the streams we created */ ret = drm_atomic_helper_check_planes(dev, state); if (ret) {