From: Rob Clark <r...@ti.com>
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 at ti.com>
---
drivers/staging/omapdrm/omap_gem.c | 30 ++++++++++++++++++++++++++++++
1 files changed, 30 insertions(+), 0 deletions(-)
diff --git a/drivers/staging/omapdrm/omap_gem.c
b/drivers/staging/omapdrm/omap_gem.c
index 63490f7..e0ebd1d 100644
--- 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;
}
--
1.7.5.4
