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 bf394d28548c3c0a01e113fdef20ddb6cd2df106 ]
The addition of register read-back in VCN v5.0.1 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_v5_0_1.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/vcn_v5_0_1.c b/drivers/gpu/drm/amd/amdgpu/vcn_v5_0_1.c index e0e84ef7f5686..9a142a21aaea8 100644 --- a/drivers/gpu/drm/amd/amdgpu/vcn_v5_0_1.c +++ b/drivers/gpu/drm/amd/amdgpu/vcn_v5_0_1.c @@ -809,6 +809,11 @@ static int vcn_v5_0_1_start(struct amdgpu_vcn_inst *vinst) WREG32_SOC15(VCN, vcn_inst, regVCN_RB_ENABLE, tmp); fw_shared->sq.queue_mode &= ~(FW_QUEUE_RING_RESET | FW_QUEUE_DPG_HOLD_OFF);
+ /* Keeping one read-back to ensure all register writes are done, + * otherwise it may introduce race conditions. + */ + RREG32_SOC15(VCN, vcn_inst, regUVD_STATUS); + return 0; }
@@ -843,6 +848,11 @@ static void vcn_v5_0_1_stop_dpg_mode(struct amdgpu_vcn_inst *vinst) /* disable dynamic power gating mode */ WREG32_P(SOC15_REG_OFFSET(VCN, vcn_inst, regUVD_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, vcn_inst, regUVD_STATUS); }
/** @@ -918,6 +928,11 @@ static int vcn_v5_0_1_stop(struct amdgpu_vcn_inst *vinst) /* clear status */ WREG32_SOC15(VCN, vcn_inst, regUVD_STATUS, 0);
+ /* Keeping one read-back to ensure all register writes are done, + * otherwise it may introduce race conditions. + */ + RREG32_SOC15(VCN, vcn_inst, regUVD_STATUS); + return 0; }