drm/omap: GEM, deal with cache

Uncached/writecombine buffers need to be clean before creating uc/wc
userspace mappings, lest dirty cache lines fall down and corrupt the
contents of the buffer.

Signed-off-by: Rob Clark <rob@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/staging/omapdrm/omap_gem.c b/drivers/staging/omapdrm/omap_gem.c
index 63490f7..e0ebd1d 100644 (file)
--- a/drivers/staging/omapdrm/omap_gem.c
+++ b/drivers/staging/omapdrm/omap_gem.c
@@ -84,6 +84,9 @@ struct omap_gem_object {
         */
        struct page **pages;
 
+       /** addresses corresponding to pages in above array */
+       dma_addr_t *addrs;
+
        /**
         * Virtual address, if mapped.
         */
@@ -208,6 +211,19 @@ static int omap_gem_attach_pages(struct drm_gem_object *obj)
                return PTR_ERR(pages);
        }
 
+       /* for non-cached buffers, ensure the new pages are clean because
+        * DSS, GPU, etc. are not cache coherent:
+        */
+       if (omap_obj->flags & (OMAP_BO_WC|OMAP_BO_UNCACHED)) {
+               int i, npages = obj->size >> PAGE_SHIFT;
+               dma_addr_t *addrs = kmalloc(npages * sizeof(addrs), GFP_KERNEL);
+               for (i = 0; i < npages; i++) {
+                       addrs[i] = dma_map_page(obj->dev->dev, pages[i],
+                                       0, PAGE_SIZE, DMA_BIDIRECTIONAL);
+               }
+               omap_obj->addrs = addrs;
+       }
+
        omap_obj->pages = pages;
        return 0;
 }
@@ -216,6 +232,20 @@ static int omap_gem_attach_pages(struct drm_gem_object *obj)
 static void omap_gem_detach_pages(struct drm_gem_object *obj)
 {
        struct omap_gem_object *omap_obj = to_omap_bo(obj);
+
+       /* for non-cached buffers, ensure the new pages are clean because
+        * DSS, GPU, etc. are not cache coherent:
+        */
+       if (omap_obj->flags & (OMAP_BO_WC|OMAP_BO_UNCACHED)) {
+               int i, npages = obj->size >> PAGE_SHIFT;
+               for (i = 0; i < npages; i++) {
+                       dma_unmap_page(obj->dev->dev, omap_obj->addrs[i],
+                                       PAGE_SIZE, DMA_BIDIRECTIONAL);
+               }
+               kfree(omap_obj->addrs);
+               omap_obj->addrs = NULL;
+       }
+
        _drm_gem_put_pages(obj, omap_obj->pages, true, false);
        omap_obj->pages = NULL;
 }