[AMD Official Use Only - AMD Internal Distribution Only] The series is
`Reviewed-by: Ruijing Dong <[email protected]>` -----Original Message----- From: Wu, David <[email protected]> Sent: Wednesday, May 21, 2025 4:24 PM To: [email protected]; Koenig, Christian <[email protected]> Cc: Deucher, Alexander <[email protected]>; Liu, Leo <[email protected]>; Jiang, Sonny <[email protected]>; Dong, Ruijing <[email protected]> Subject: [PATCH v3 9/9] drm/amdgpu: read back register after written The addition of register read-back in VCN v5.0.1 is intended to prevent potential race conditions. Signed-off-by: David (Ming Qiang) Wu <[email protected]> --- 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 1e9d2aedf2799..338cf43c45fe7 100644 --- a/drivers/gpu/drm/amd/amdgpu/vcn_v5_0_1.c +++ b/drivers/gpu/drm/amd/amdgpu/vcn_v5_0_1.c @@ -1038,6 +1038,11 @@ 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; } @@ -1072,6 +1077,11 @@ 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); } /** @@ -1147,6 +1157,11 @@ 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; } -- 2.34.1
