drm: add flag for mapping PCI DMA buffers read-only.

Add DRM_PCI_BUFFER_RO flag for mapping PCI DMA buffer read-only. An additional
flag is needed, since PCI DMA buffers do not have an associated map.

Signed-off-by: Dave Airlie <airlied@linux.ie>

1 files changed, 7 insertions, 3 deletions

diff --git a/drivers/char/drm/drm_bufs.c b/drivers/char/drm/drm_bufs.c
index 6eafff13dab6..9f65f5697ba8 100644
--- a/drivers/char/drm/drm_bufs.c
+++ b/drivers/char/drm/drm_bufs.c
@@ -887,6 +887,9 @@ int drm_addbufs_pci(drm_device_t * dev, drm_buf_desc_t * request)
         request->count = entry->buf_count;
         request->size = size;
 
+        if (request->flags & _DRM_PCI_BUFFER_RO)
+                dma->flags = _DRM_DMA_USE_PCI_RO;
+
         atomic_dec(&dev->buf_alloc);
         return 0;
 
@@ -1471,9 +1474,10 @@ int drm_freebufs(struct inode *inode, struct file *filp,
  * \param arg pointer to a drm_buf_map structure.
  * \return zero on success or a negative number on failure.
  *
- * Maps the AGP or SG buffer region with do_mmap(), and copies information
- * about each buffer into user space. The PCI buffers are already mapped on the
- * addbufs_pci() call.
+ * Maps the AGP, SG or PCI buffer region with do_mmap(), and copies information
+ * about each buffer into user space. For PCI buffers, it calls do_mmap() with
+ * offset equal to 0, which drm_mmap() interpretes as PCI buffers and calls
+ * drm_mmap_dma().
  */
 int drm_mapbufs(struct inode *inode, struct file *filp,
                 unsigned int cmd, unsigned long arg)