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>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
index 60dfce889ecf..4663fbcfda28 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -745,7 +745,7 @@ int radeon_ttm_init(struct radeon_device *rdev)
         }
         DRM_INFO("radeon: %uM of GTT memory ready.\n",
                  (unsigned)(rdev->mc.gtt_size / (1024 * 1024)));
-        rdev->mman.bdev.dev_mapping = rdev->ddev->dev_mapping;
+        rdev->mman.bdev.dev_mapping = rdev->ddev->anon_inode->i_mapping;
 
         r = radeon_ttm_debugfs_init(rdev);
         if (r) {