On 6/17/25 10:26 AM, Greg Kroah-Hartman wrote:
6.12-stable review patch. If anyone has any objections, please let me know.
From: David (Ming Qiang) Wu David.Wu3@amd.com
[ Upstream commit 07c9db090b86e5211188e1b351303fbc673378cf ]
On VCN v4.0.5 there is a race condition where the WPTR is not updated after starting from idle when doorbell is used. Adding register read-back after written at function end is to ensure all register writes are done before they can be used.
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/12528 Signed-off-by: David (Ming Qiang) Wu David.Wu3@amd.com Reviewed-by: Mario Limonciello mario.limonciello@amd.com Tested-by: Mario Limonciello mario.limonciello@amd.com Reviewed-by: Alex Deucher alexander.deucher@amd.com Reviewed-by: Ruijing Dong ruijing.dong@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Stable-dep-of: ee7360fc27d6 ("drm/amdgpu: read back register after written for VCN v4.0.5") Signed-off-by: Sasha Levin sashal@kernel.org
drivers/gpu/drm/amd/amdgpu/vcn_v4_0_5.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/vcn_v4_0_5.c b/drivers/gpu/drm/amd/amdgpu/vcn_v4_0_5.c index e0b02bf1c5639..db33a2b9109aa 100644 --- a/drivers/gpu/drm/amd/amdgpu/vcn_v4_0_5.c +++ b/drivers/gpu/drm/amd/amdgpu/vcn_v4_0_5.c @@ -985,6 +985,10 @@ static int vcn_v4_0_5_start_dpg_mode(struct amdgpu_device *adev, int inst_idx, b 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, regVCN_RB1_DB_CTRL);
- return 0; }
@@ -1169,6 +1173,10 @@ static int vcn_v4_0_5_start(struct amdgpu_device *adev) 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, regVCN_RB_ENABLE);
The scope of this change is incorrect. It should be in the for loop above.
IE here:
for (i = 0; i < adev->vcn.num_vcn_inst; ++i) {
>>
}
return 0;
return 0; }