drm/amdgpu: Add a UAPI flag for user to call mem_sync

When this flag is set in the CS IB flags, it causes
a memory cache flush of the GFX.

v2:
Move new flag to drm_amdgpu_cs_chunk_ib.flags
Bump up UAPI version
Remove condition on job != null to emit mem_sync

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Luben Tuikov <luben.tuikov@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -86,9 +86,10 @@
  * - 3.35.0 - Add drm_amdgpu_info_device::tcc_disabled_mask
  * - 3.36.0 - Allow reading more status registers on si/cik
  * - 3.37.0 - L2 is invalidated before SDMA IBs, needed for correctness
+ * - 3.38.0 - Add AMDGPU_IB_FLAG_EMIT_MEM_SYNC
  */
 #define KMS_DRIVER_MAJOR	3
-#define KMS_DRIVER_MINOR	37
+#define KMS_DRIVER_MINOR	38
 #define KMS_DRIVER_PATCHLEVEL	0
 
 int amdgpu_vram_limit = 0;

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

@@ -189,6 +189,9 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
 		dma_fence_put(tmp);
 	}
 
+	if ((ib->flags & AMDGPU_IB_FLAG_EMIT_MEM_SYNC) && ring->funcs->emit_mem_sync)
+		ring->funcs->emit_mem_sync(ring);
+
 	if (ring->funcs->insert_start)
 		ring->funcs->insert_start(ring);
 

include/uapi/drm/amdgpu_drm.h

@@ -602,6 +602,10 @@ union drm_amdgpu_cs {
  */
 #define AMDGPU_IB_FLAGS_SECURE  (1 << 5)
 
+/* Tell KMD to flush and invalidate caches
+ */
+#define AMDGPU_IB_FLAG_EMIT_MEM_SYNC  (1 << 6)
+
 struct drm_amdgpu_cs_chunk_ib {
 	__u32 _pad;
 	/** AMDGPU_IB_FLAG_* */