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drm: use anon-inode instead of relying on cdevs

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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>
This commit is contained in:
David Herrmann
2014-01-03 14:24:19 +01:00
parent 31bbe16f6d
commit 6796cb16c0
15 changed files with 44 additions and 54 deletions
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34
drivers/gpu/drm/omapdrm/omap_gem.c
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@@ -153,24 +153,24 @@ static struct {
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;