This patch adds the missing code comment for memory barrier
WARNING: memory barrier without comment
+ mb();
WARNING: memory barrier without comment
+ mb();
Cc: Guchun Chen <guchun.chen@xxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: "Pan, Xinhui" <Xinhui.Pan@xxxxxxx>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@xxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 4f818f13dc9d..a1c214f86e4d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -305,10 +305,17 @@ size_t amdgpu_device_aper_access(struct amdgpu_device *adev, loff_t pos,
if (write) {
memcpy_toio(addr, buf, count);
+ /* Make sure contents of system memory are copied/flushed
+ * without messing up order of writes to PCI device I/O memory
+ */
mb();
amdgpu_device_flush_hdp(adev, NULL);
} else {
amdgpu_device_invalidate_hdp(adev, NULL);
+ /* Make sure contents of system memory drained/invalidated
+ * before copying contents from PCI device I/O memory
+ * to system memory
+ */
mb();
memcpy_fromio(buf, addr, count);
}
--
2.25.1
