drm/amdgpu/hdp5.2: do a posting read when flushing HDP

Need to read back to make sure the write goes through.

Cc: David Belanger <[email protected]>
Reviewed-by: Frank Min <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
Cc: [email protected]

Author: alexdeucher

drivers/gpu/drm/amd/amdgpu/hdp_v5_2.c

@@ -31,13 +31,15 @@
 static void hdp_v5_2_flush_hdp(struct amdgpu_device *adev,
 				struct amdgpu_ring *ring)
 {
-	if (!ring || !ring->funcs->emit_wreg)
+	if (!ring || !ring->funcs->emit_wreg) {
 		WREG32_NO_KIQ((adev->rmmio_remap.reg_offset + KFD_MMIO_REMAP_HDP_MEM_FLUSH_CNTL) >> 2,
 			0);
-	else
+		RREG32_NO_KIQ((adev->rmmio_remap.reg_offset + KFD_MMIO_REMAP_HDP_MEM_FLUSH_CNTL) >> 2);
+	} else {
 		amdgpu_ring_emit_wreg(ring,
 			(adev->rmmio_remap.reg_offset + KFD_MMIO_REMAP_HDP_MEM_FLUSH_CNTL) >> 2,
 			0);
+	}
 }
 
 static void hdp_v5_2_update_mem_power_gating(struct amdgpu_device *adev,