[PATCH v3 2/6] drm/msm/gem: dma_map/unmap_sgtable()

[Rob Clark]

This should functionally be a no-op for us, since we are managing our
SMMU directly (dma_map_ops is NULL), but it populates the dma_len/
dma_address's so that we can use them for setting up pgtable mappings.

This inlines sync_for_device() and sync_for_cpu() into their only
callers to avoid doubling up on the dma-mapping calls.

Tested-by: Jianfeng Liu <liujianfeng1994@xxxxxxxxx> # x1e78100 (Acer SFA14-11), v7.3-rc5 + this series, CONFIG_DMABUF_DEBUG=y
Signed-off-by: Rob Clark <robin.clark@xxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/msm/msm_gem.c | 62 ++++++++++++++---------------------
 1 file changed, 25 insertions(+), 37 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 181b9ad32672..c97395e4ea2b 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -116,34 +116,6 @@ void msm_gem_vma_put(struct drm_gem_object *obj)
 #endif
 }
 
-/*
- * Cache sync.. this is a bit over-complicated, to fit dma-mapping
- * API.  Really GPU cache is out of scope here (handled on cmdstream)
- * and all we need to do is invalidate newly allocated pages before
- * mapping to CPU as uncached/writecombine.
- *
- * On top of this, we have the added headache, that depending on
- * display generation, the display's iommu may be wired up to either
- * the toplevel drm device (mdss), or to the mdp sub-node, meaning
- * that here we either have dma-direct or iommu ops.
- *
- * Let this be a cautionary tail of abstraction gone wrong.
- */
-
-static void sync_for_device(struct msm_gem_object *msm_obj)
-{
-	struct device *dev = msm_obj->base.dev->dev;
-
-	dma_map_sgtable(dev, msm_obj->sgt, DMA_BIDIRECTIONAL, 0);
-}
-
-static void sync_for_cpu(struct msm_gem_object *msm_obj)
-{
-	struct device *dev = msm_obj->base.dev->dev;
-
-	dma_unmap_sgtable(dev, msm_obj->sgt, DMA_BIDIRECTIONAL, 0);
-}
-
 static void update_lru_active(struct drm_gem_object *obj)
 {
 	struct msm_drm_private *priv = obj->dev->dev_private;
@@ -201,6 +173,7 @@ static struct page **get_pages(struct drm_gem_object *obj)
 		struct drm_device *dev = obj->dev;
 		struct page **p;
 		size_t npages = obj->size >> PAGE_SHIFT;
+		unsigned map_attrs = DMA_ATTR_SKIP_CPU_SYNC;
 
 		p = drm_gem_get_pages(obj);
 
@@ -219,13 +192,20 @@ static struct page **get_pages(struct drm_gem_object *obj)
 			goto error;
 		}
 
-		update_device_mem(dev->dev_private, obj->size);
-
-		/* For non-cached buffers, ensure the new pages are clean
-		 * because display controller, GPU, etc. are not coherent:
-		 */
+		/* For non-cached buffers, ensure the new pages are clean. */
 		if (msm_obj->flags & MSM_BO_WC)
-			sync_for_device(msm_obj);
+			map_attrs = 0;
+
+		ret = dma_map_sgtable(drm_dev_dma_dev(obj->dev),
+				      msm_obj->sgt,
+				      DMA_BIDIRECTIONAL,
+				      map_attrs);
+		if (ret) {
+			DRM_DEV_ERROR(dev->dev, "could not map sgtable: %d\n", ret);
+			goto error;
+		}
+
+		update_device_mem(dev->dev_private, obj->size);
 
 		update_lru(obj);
 	}
@@ -233,6 +213,8 @@ static struct page **get_pages(struct drm_gem_object *obj)
 	return msm_obj->pages;
 
 error:
+	if (!IS_ERR(msm_obj->sgt))
+		drm_prime_gem_destroy(obj, msm_obj->sgt);
 	msm_obj->sgt = NULL;
 
 	drm_gem_put_pages(obj, msm_obj->pages, false, false);
@@ -253,12 +235,18 @@ static void put_pages(struct drm_gem_object *obj)
 		drm_gpuvm_bo_gem_evict(obj, true);
 
 	if (msm_obj->pages) {
+		unsigned unmap_attrs = DMA_ATTR_SKIP_CPU_SYNC;
+
 		/* For non-cached buffers, ensure the new
-		 * pages are clean because display controller,
-		 * GPU, etc. are not coherent:
+		 * pages are clean:
 		 */
 		if (msm_obj->flags & MSM_BO_WC)
-			sync_for_cpu(msm_obj);
+			unmap_attrs = 0;
+
+		dma_unmap_sgtable(drm_dev_dma_dev(obj->dev),
+				  msm_obj->sgt,
+				  DMA_BIDIRECTIONAL,
+				  unmap_attrs);
 
 		sg_free_table(msm_obj->sgt);
 		kfree(msm_obj->sgt);
-- 
2.56.0