[Nouveau] [PATCH] instmem/gk20a: add write barrier when releasing DMA object

[Alexandre Courbot]

When using the DMA-API for instmem, we may obtain a write-combined
mapping. For such cases, add a write barrier in
gk20a_instobj_release_dma() to make sure that all writes have reached
memory at this time.

Signed-off-by: Alexandre Courbot <acourbot at nvidia.com>
---
 drm/nouveau/nvkm/subdev/instmem/gk20a.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drm/nouveau/nvkm/subdev/instmem/gk20a.c b/drm/nouveau/nvkm/subdev/instmem/gk20a.c
index 4c20fec64d96..6b8f2a19b2d9 100644
--- a/drm/nouveau/nvkm/subdev/instmem/gk20a.c
+++ b/drm/nouveau/nvkm/subdev/instmem/gk20a.c
@@ -228,6 +228,8 @@ gk20a_instobj_release_dma(struct nvkm_memory *memory)
 	struct gk20a_instmem *imem = node->imem;
 	struct nvkm_ltc *ltc = imem->base.subdev.device->ltc;
 
+	/* in case we got a write-combined mapping */
+	wmb();
 	nvkm_ltc_invalidate(ltc);
 }
 
-- 
2.7.2