6.15-stable review patch. If anyone has any objections, please let me know.
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From: David (Ming Qiang) Wu David.Wu3@amd.com
[ Upstream commit d9e688b9148bb23629d32017344888dd67ec2ab1 ]
The addition of register read-back in VCN v2.5 is intended to prevent potential race conditions.
Reviewed-by: Ruijing Dong ruijing.dong@amd.com Signed-off-by: David (Ming Qiang) Wu David.Wu3@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c b/drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c index 3eec1b8feaeea..58b527a6b795f 100644 --- a/drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c +++ b/drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c @@ -1158,6 +1158,11 @@ static int vcn_v2_5_start_dpg_mode(struct amdgpu_vcn_inst *vinst, bool indirect) WREG32_P(SOC15_REG_OFFSET(VCN, inst_idx, mmUVD_POWER_STATUS), 0, ~UVD_POWER_STATUS__STALL_DPG_POWER_UP_MASK);
+ /* Keeping one read-back to ensure all register writes are done, + * otherwise it may introduce race conditions. + */ + RREG32_SOC15(VCN, inst_idx, mmUVD_STATUS); + return 0; }
@@ -1343,6 +1348,11 @@ static int vcn_v2_5_start(struct amdgpu_vcn_inst *vinst) WREG32_SOC15(VCN, i, mmUVD_RB_SIZE2, ring->ring_size / 4); fw_shared->multi_queue.encode_lowlatency_queue_mode &= ~FW_QUEUE_RING_RESET;
+ /* Keeping one read-back to ensure all register writes are done, + * otherwise it may introduce race conditions. + */ + RREG32_SOC15(VCN, i, mmUVD_STATUS); + return 0; }
@@ -1569,6 +1579,11 @@ static int vcn_v2_5_stop_dpg_mode(struct amdgpu_vcn_inst *vinst) WREG32_P(SOC15_REG_OFFSET(VCN, inst_idx, mmUVD_POWER_STATUS), 0, ~UVD_POWER_STATUS__UVD_PG_MODE_MASK);
+ /* Keeping one read-back to ensure all register writes are done, + * otherwise it may introduce race conditions. + */ + RREG32_SOC15(VCN, inst_idx, mmUVD_STATUS); + return 0; }
@@ -1635,6 +1650,10 @@ static int vcn_v2_5_stop(struct amdgpu_vcn_inst *vinst) UVD_POWER_STATUS__UVD_POWER_STATUS_MASK, ~UVD_POWER_STATUS__UVD_POWER_STATUS_MASK);
+ /* Keeping one read-back to ensure all register writes are done, + * otherwise it may introduce race conditions. + */ + RREG32_SOC15(VCN, i, mmUVD_STATUS); done: if (adev->pm.dpm_enabled) amdgpu_dpm_enable_vcn(adev, false, i);