Overlapping or nested mappings of the same BO are not allowed by the
semantics of the GEM vmap/vunmap operations. Concurent access to the
GEM object is prevented by reservation locks.
So we don't need the reference counter in the GEM VRAM object. Remove
it.
Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
---
drivers/gpu/drm/drm_gem_vram_helper.c | 19 ++++---------------
include/drm/drm_gem_vram_helper.h | 17 +++--------------
2 files changed, 7 insertions(+), 29 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c
index 760d77c6c3c0..276e8f8ea663 100644
--- a/drivers/gpu/drm/drm_gem_vram_helper.c
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -113,7 +113,6 @@ static void drm_gem_vram_cleanup(struct drm_gem_vram_object *gbo)
* up; only release the GEM object.
*/
- WARN_ON(gbo->vmap_use_count);
WARN_ON(dma_buf_map_is_set(&gbo->map));
drm_gem_object_release(&gbo->bo.base);
@@ -384,15 +383,10 @@ static int drm_gem_vram_kmap_locked(struct drm_gem_vram_object *gbo,
{
int ret;
- if (gbo->vmap_use_count > 0)
- goto out;
-
ret = ttm_bo_vmap(&gbo->bo, &gbo->map);
if (ret)
return ret;
-out:
- ++gbo->vmap_use_count;
*map = gbo->map;
return 0;
@@ -403,15 +397,9 @@ static void drm_gem_vram_kunmap_locked(struct drm_gem_vram_object *gbo,
{
struct drm_device *dev = gbo->bo.base.dev;
- if (drm_WARN_ON_ONCE(dev, !gbo->vmap_use_count))
- return;
-
if (drm_WARN_ON_ONCE(dev, !dma_buf_map_is_equal(&gbo->map, map)))
return; /* BUG: map not mapped from this BO */
- if (--gbo->vmap_use_count > 0)
- return;
-
/*
* Permanently mapping and unmapping buffers adds overhead from
* updating the page tables and creates debugging output. Therefore,
@@ -545,12 +533,13 @@ static void drm_gem_vram_bo_driver_move_notify(struct drm_gem_vram_object *gbo,
struct ttm_resource *new_mem)
{
struct ttm_buffer_object *bo = &gbo->bo;
- struct drm_device *dev = bo->base.dev;
+ struct dma_buf_map *map = &gbo->map;
- if (drm_WARN_ON_ONCE(dev, gbo->vmap_use_count))
+ if (dma_buf_map_is_null(map))
return;
- ttm_bo_vunmap(bo, &gbo->map);
+ ttm_bo_vunmap(bo, map);
+ dma_buf_map_clear(map);
}
static int drm_gem_vram_bo_driver_move(struct drm_gem_vram_object *gbo,
diff --git a/include/drm/drm_gem_vram_helper.h b/include/drm/drm_gem_vram_helper.h
index a4bac02249c2..48af238b5ca9 100644
--- a/include/drm/drm_gem_vram_helper.h
+++ b/include/drm/drm_gem_vram_helper.h
@@ -41,25 +41,14 @@ struct vm_area_struct;
* dedicated memory. The buffer object can be evicted to system memory if
* video memory becomes scarce.
*
- * GEM VRAM objects perform reference counting for pin and mapping
- * operations. So a buffer object that has been pinned N times with
- * drm_gem_vram_pin() must be unpinned N times with
- * drm_gem_vram_unpin(). The same applies to pairs of
- * drm_gem_vram_kmap() and drm_gem_vram_kunmap(), as well as pairs of
- * drm_gem_vram_vmap() and drm_gem_vram_vunmap().
+ * GEM VRAM objects perform reference counting for pin operations. So a
+ * buffer object that has been pinned N times with drm_gem_vram_pin() must
+ * be unpinned N times with drm_gem_vram_unpin().
*/
struct drm_gem_vram_object {
struct ttm_buffer_object bo;
struct dma_buf_map map;
- /**
- * @vmap_use_count:
- *
- * Reference count on the virtual address.
- * The address are un-mapped when the count reaches zero.
- */
- unsigned int vmap_use_count;
-
/* Supported placements are %TTM_PL_VRAM and %TTM_PL_SYSTEM */
struct ttm_placement placement;
struct ttm_place placements[2];
--
2.29.2
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