The addition of register read-back in VCN v1.0 is intended to prevent potential race conditions.
Signed-off-by: David (Ming Qiang) Wu <[email protected]> --- drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c b/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c index 21b57c29bf7d..f56b623713c9 100644 --- a/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c +++ b/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c @@ -1009,6 +1009,11 @@ static int vcn_v1_0_start_spg_mode(struct amdgpu_vcn_inst *vinst) jpeg_v1_0_start(adev, 0); + /* Keeping one read-back to ensure all register writes are done, otherwise + * it may introduce race conditions + */ + RREG32_SOC15(UVD, 0, mmUVD_RBC_RB_WPTR); + return 0; } @@ -1154,6 +1159,11 @@ static int vcn_v1_0_start_dpg_mode(struct amdgpu_vcn_inst *vinst) jpeg_v1_0_start(adev, 1); + /* Keeping one read-back to ensure all register writes are done, otherwise + * it may introduce race conditions + */ + RREG32_SOC15(UVD, 0, mmUVD_RBC_RB_WPTR); + return 0; } -- 2.49.0
