6.12-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
commit ee7360fc27d6045510f8fe459b5649b2af27811a upstream.
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 (cherry picked from commit 07c9db090b86e5211188e1b351303fbc673378cf) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/amd/amdgpu/vcn_v4_0_5.c | 8 ++++++++ 1 file changed, 8 insertions(+)
--- 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(str 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 amdgp 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); + return 0; }