1 files changed, 42 insertions, 5 deletions

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 8b78554cfde3..8cf6362e64bf 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -32,6 +32,46 @@ static bool use_pages(struct drm_gem_object *obj)
         return !msm_obj->vram_node;
 }
 
+/*
+ * 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;
+
+        if (get_dma_ops(dev)) {
+                dma_sync_sg_for_device(dev, msm_obj->sgt->sgl,
+                        msm_obj->sgt->nents, DMA_BIDIRECTIONAL);
+        } else {
+                dma_map_sg(dev, msm_obj->sgt->sgl,
+                        msm_obj->sgt->nents, DMA_BIDIRECTIONAL);
+        }
+}
+
+static void sync_for_cpu(struct msm_gem_object *msm_obj)
+{
+        struct device *dev = msm_obj->base.dev->dev;
+
+        if (get_dma_ops(dev)) {
+                dma_sync_sg_for_cpu(dev, msm_obj->sgt->sgl,
+                        msm_obj->sgt->nents, DMA_BIDIRECTIONAL);
+        } else {
+                dma_unmap_sg(dev, msm_obj->sgt->sgl,
+                        msm_obj->sgt->nents, DMA_BIDIRECTIONAL);
+        }
+}
+
 /* allocate pages from VRAM carveout, used when no IOMMU: */
 static struct page **get_pages_vram(struct drm_gem_object *obj, int npages)
 {
@@ -97,8 +137,7 @@ static struct page **get_pages(struct drm_gem_object *obj)
                  * because display controller, GPU, etc. are not coherent:
                  */
                 if (msm_obj->flags & (MSM_BO_WC|MSM_BO_UNCACHED))
-                        dma_map_sg(dev->dev, msm_obj->sgt->sgl,
-                                        msm_obj->sgt->nents, DMA_BIDIRECTIONAL);
+                        sync_for_device(msm_obj);
         }
 
         return msm_obj->pages;
@@ -127,9 +166,7 @@ static void put_pages(struct drm_gem_object *obj)
                          * GPU, etc. are not coherent:
                          */
                         if (msm_obj->flags & (MSM_BO_WC|MSM_BO_UNCACHED))
-                                dma_unmap_sg(obj->dev->dev, msm_obj->sgt->sgl,
-                                             msm_obj->sgt->nents,
-                                             DMA_BIDIRECTIONAL);
+                                sync_for_cpu(msm_obj);
 
                         sg_free_table(msm_obj->sgt);
                         kfree(msm_obj->sgt);