drm: use anon-inode instead of relying on cdevs
DRM drivers share a common address_space across all character-devices of a
single DRM device. This allows simple buffer eviction and mapping-control.
However, DRM core currently waits for the first ->open() on any char-dev
to mark the underlying inode as backing inode of the device. This delayed
initialization causes ugly conditions all over the place:
if (dev->dev_mapping)
do_sth();
To avoid delayed initialization and to stop reusing the inode of the
char-dev, we allocate an anonymous inode for each DRM device and reset
filp->f_mapping to it on ->open().
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
index 5aec3e8..c8d9727 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem.c
@@ -153,24 +153,24 @@
static void evict_entry(struct drm_gem_object *obj,
enum tiler_fmt fmt, struct usergart_entry *entry)
{
- if (obj->dev->dev_mapping) {
- struct omap_gem_object *omap_obj = to_omap_bo(obj);
- int n = usergart[fmt].height;
- size_t size = PAGE_SIZE * n;
- loff_t off = mmap_offset(obj) +
- (entry->obj_pgoff << PAGE_SHIFT);
- const int m = 1 + ((omap_obj->width << fmt) / PAGE_SIZE);
- if (m > 1) {
- int i;
- /* if stride > than PAGE_SIZE then sparse mapping: */
- for (i = n; i > 0; i--) {
- unmap_mapping_range(obj->dev->dev_mapping,
- off, PAGE_SIZE, 1);
- off += PAGE_SIZE * m;
- }
- } else {
- unmap_mapping_range(obj->dev->dev_mapping, off, size, 1);
+ struct omap_gem_object *omap_obj = to_omap_bo(obj);
+ int n = usergart[fmt].height;
+ size_t size = PAGE_SIZE * n;
+ loff_t off = mmap_offset(obj) +
+ (entry->obj_pgoff << PAGE_SHIFT);
+ const int m = 1 + ((omap_obj->width << fmt) / PAGE_SIZE);
+
+ if (m > 1) {
+ int i;
+ /* if stride > than PAGE_SIZE then sparse mapping: */
+ for (i = n; i > 0; i--) {
+ unmap_mapping_range(obj->dev->anon_inode->i_mapping,
+ off, PAGE_SIZE, 1);
+ off += PAGE_SIZE * m;
}
+ } else {
+ unmap_mapping_range(obj->dev->anon_inode->i_mapping,
+ off, size, 1);
}
entry->obj = NULL;