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drm/amdgpu/vcn4: read back register after written

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The addition of register read-back in VCN v4.0.0 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>
This commit is contained in:
David (Ming Qiang) Wu 2025-05-14 18:55:27 -04:00 committed by Alex Deucher
parent b7a4842a91
commit a3810a5e37
1 changed files with 20 additions and 0 deletions
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20
drivers/gpu/drm/amd/amdgpu/vcn_v4_0.c
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@ -1122,6 +1122,11 @@ static int vcn_v4_0_start_dpg_mode(struct amdgpu_vcn_inst *vinst, bool indirect)
ring->doorbell_index << VCN_RB1_DB_CTRL__OFFSET__SHIFT |
VCN_RB1_DB_CTRL__EN_MASK);
/* Keeping one read-back to ensure all register writes are done,
* otherwise it may introduce race conditions.
*/
RREG32_SOC15(VCN, inst_idx, regUVD_STATUS);
return 0;
}
@ -1303,6 +1308,11 @@ static int vcn_v4_0_start(struct amdgpu_vcn_inst *vinst)
WREG32_SOC15(VCN, i, 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, i, regUVD_STATUS);
return 0;
}
@ -1583,6 +1593,11 @@ static void vcn_v4_0_stop_dpg_mode(struct amdgpu_vcn_inst *vinst)
/* disable dynamic power gating mode */
WREG32_P(SOC15_REG_OFFSET(VCN, inst_idx, 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, inst_idx, regUVD_STATUS);
}
/**
@ -1666,6 +1681,11 @@ static int vcn_v4_0_stop(struct amdgpu_vcn_inst *vinst)
/* enable VCN power gating */
vcn_v4_0_enable_static_power_gating(vinst);
/* Keeping one read-back to ensure all register writes are done,
* otherwise it may introduce race conditions.
*/
RREG32_SOC15(VCN, i, regUVD_STATUS);
done:
if (adev->pm.dpm_enabled)
amdgpu_dpm_enable_vcn(adev, false, i);