[v5,2/4] drm/gem: convert to new unified vma manager

Commit Message

David Herrmann July 24, 2013, 7:07 p.m. UTC

Use the new vma manager instead of the old hashtable. Also convert all
drivers to use the new convenience helpers. This drops all the
(map_list.hash.key << PAGE_SHIFT) non-sense.

Locking and access-management is exactly the same as before with an
additional lock inside of the vma-manager, which strictly wouldn't be
needed for gem.

v2:
 - rebase on drm-next
 - init nodes via drm_vma_node_reset() in drm_gem.c
v3:
 - fix tegra
v4:
 - remove duplicate if (drm_vma_node_has_offset()) checks
 - inline now trivial drm_vma_node_offset_addr() calls
v5:
 - skip node-reset on gem-init due to kzalloc()
 - do not allow mapping gem-objects with offsets (backwards compat)
 - remove unneccessary casts

Cc: Inki Dae <[e-mail]>
Cc: Rob Clark <[e-mail]>
Cc: Dave Airlie <[e-mail]>
Cc: Thierry Reding <[e-mail]>
Signed-off-by: David Herrmann <[e-mail]>
Acked-by: Patrik Jakobsson <[e-mail]>
Reviewed-by: Daniel Vetter <[e-mail]>
---
 drivers/gpu/drm/drm_gem.c                  | 89 +++++-------------------------
 drivers/gpu/drm/drm_gem_cma_helper.c       | 16 ++----
 drivers/gpu/drm/exynos/exynos_drm_gem.c    | 14 ++---
 drivers/gpu/drm/gma500/gem.c               | 15 ++---
 drivers/gpu/drm/i915/i915_gem.c            | 10 ++--
 drivers/gpu/drm/omapdrm/omap_gem.c         | 28 +++++-----
 drivers/gpu/drm/omapdrm/omap_gem_helpers.c | 49 +---------------
 drivers/gpu/drm/udl/udl_gem.c              | 13 ++---
 drivers/gpu/host1x/drm/gem.c               |  5 +-
 include/drm/drmP.h                         |  7 +--
 include/uapi/drm/drm.h                     |  2 +-
 11 files changed, 62 insertions(+), 186 deletions(-)

Patch

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 1ad9e7e..3613b50 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -37,6 +37,7 @@ 
 #include <linux/shmem_fs.h>
 #include <linux/dma-buf.h>
 #include <drm/drmP.h>
+#include <drm/drm_vma_manager.h>
 
 /** @file drm_gem.c
  *
@@ -102,14 +103,9 @@  drm_gem_init(struct drm_device *dev)
 	}
 
 	dev->mm_private = mm;
-
-	if (drm_ht_create(&mm->offset_hash, 12)) {
-		kfree(mm);
-		return -ENOMEM;
-	}
-
-	drm_mm_init(&mm->offset_manager, DRM_FILE_PAGE_OFFSET_START,
-		    DRM_FILE_PAGE_OFFSET_SIZE);
+	drm_vma_offset_manager_init(&mm->vma_manager,
+				    DRM_FILE_PAGE_OFFSET_START,
+				    DRM_FILE_PAGE_OFFSET_SIZE);
 
 	return 0;
 }
@@ -119,8 +115,7 @@  drm_gem_destroy(struct drm_device *dev)
 {
 	struct drm_gem_mm *mm = dev->mm_private;
 
-	drm_mm_takedown(&mm->offset_manager);
-	drm_ht_remove(&mm->offset_hash);
+	drm_vma_offset_manager_destroy(&mm->vma_manager);
 	kfree(mm);
 	dev->mm_private = NULL;
 }
@@ -302,12 +297,8 @@  drm_gem_free_mmap_offset(struct drm_gem_object *obj)
 {
 	struct drm_device *dev = obj->dev;
 	struct drm_gem_mm *mm = dev->mm_private;
-	struct drm_map_list *list = &obj->map_list;
 
-	drm_ht_remove_item(&mm->offset_hash, &list->hash);
-	drm_mm_put_block(list->file_offset_node);
-	kfree(list->map);
-	list->map = NULL;
+	drm_vma_offset_remove(&mm->vma_manager, &obj->vma_node);
 }
 EXPORT_SYMBOL(drm_gem_free_mmap_offset);
 
@@ -327,54 +318,9 @@  drm_gem_create_mmap_offset(struct drm_gem_object *obj)
 {
 	struct drm_device *dev = obj->dev;
 	struct drm_gem_mm *mm = dev->mm_private;
-	struct drm_map_list *list;
-	struct drm_local_map *map;
-	int ret;
-
-	/* Set the object up for mmap'ing */
-	list = &obj->map_list;
-	list->map = kzalloc(sizeof(struct drm_map_list), GFP_KERNEL);
-	if (!list->map)
-		return -ENOMEM;
-
-	map = list->map;
-	map->type = _DRM_GEM;
-	map->size = obj->size;
-	map->handle = obj;
-
-	/* Get a DRM GEM mmap offset allocated... */
-	list->file_offset_node = drm_mm_search_free(&mm->offset_manager,
-			obj->size / PAGE_SIZE, 0, false);
-
-	if (!list->file_offset_node) {
-		DRM_ERROR("failed to allocate offset for bo %d\n", obj->name);
-		ret = -ENOSPC;
-		goto out_free_list;
-	}
 
-	list->file_offset_node = drm_mm_get_block(list->file_offset_node,
-			obj->size / PAGE_SIZE, 0);
-	if (!list->file_offset_node) {
-		ret = -ENOMEM;
-		goto out_free_list;
-	}
-
-	list->hash.key = list->file_offset_node->start;
-	ret = drm_ht_insert_item(&mm->offset_hash, &list->hash);
-	if (ret) {
-		DRM_ERROR("failed to add to map hash\n");
-		goto out_free_mm;
-	}
-
-	return 0;
-
-out_free_mm:
-	drm_mm_put_block(list->file_offset_node);
-out_free_list:
-	kfree(list->map);
-	list->map = NULL;
-
-	return ret;
+	return drm_vma_offset_add(&mm->vma_manager, &obj->vma_node,
+				  obj->size / PAGE_SIZE);
 }
 EXPORT_SYMBOL(drm_gem_create_mmap_offset);
 
@@ -703,8 +649,8 @@  int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 	struct drm_file *priv = filp->private_data;
 	struct drm_device *dev = priv->minor->dev;
 	struct drm_gem_mm *mm = dev->mm_private;
-	struct drm_local_map *map = NULL;
-	struct drm_hash_item *hash;
+	struct drm_gem_object *obj;
+	struct drm_vma_offset_node *node;
 	int ret = 0;
 
 	if (drm_device_is_unplugged(dev))
@@ -712,21 +658,16 @@  int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 
 	mutex_lock(&dev->struct_mutex);
 
-	if (drm_ht_find_item(&mm->offset_hash, vma->vm_pgoff, &hash)) {
+	node = drm_vma_offset_exact_lookup(&mm->vma_manager, vma->vm_pgoff,
+					   vma_pages(vma));
+	if (!node) {
 		mutex_unlock(&dev->struct_mutex);
 		return drm_mmap(filp, vma);
 	}
 
-	map = drm_hash_entry(hash, struct drm_map_list, hash)->map;
-	if (!map ||
-	    ((map->flags & _DRM_RESTRICTED) && !capable(CAP_SYS_ADMIN))) {
-		ret =  -EPERM;
-		goto out_unlock;
-	}
-
-	ret = drm_gem_mmap_obj(map->handle, map->size, vma);
+	obj = container_of(node, struct drm_gem_object, vma_node);
+	ret = drm_gem_mmap_obj(obj, drm_vma_node_size(node), vma);
 
-out_unlock:
 	mutex_unlock(&dev->struct_mutex);
 
 	return ret;
diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index ece72a8..847f091 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -27,11 +27,7 @@ 
 #include <drm/drmP.h>
 #include <drm/drm.h>
 #include <drm/drm_gem_cma_helper.h>
-
-static unsigned int get_gem_mmap_offset(struct drm_gem_object *obj)
-{
-	return (unsigned int)obj->map_list.hash.key << PAGE_SHIFT;
-}
+#include <drm/drm_vma_manager.h>
 
 /*
  * __drm_gem_cma_create - Create a GEM CMA object without allocating memory
@@ -172,8 +168,7 @@  void drm_gem_cma_free_object(struct drm_gem_object *gem_obj)
 {
 	struct drm_gem_cma_object *cma_obj;
 
-	if (gem_obj->map_list.map)
-		drm_gem_free_mmap_offset(gem_obj);
+	drm_gem_free_mmap_offset(gem_obj);
 
 	cma_obj = to_drm_gem_cma_obj(gem_obj);
 
@@ -237,7 +232,7 @@  int drm_gem_cma_dumb_map_offset(struct drm_file *file_priv,
 		return -EINVAL;
 	}
 
-	*offset = get_gem_mmap_offset(gem_obj);
+	*offset = drm_vma_node_offset_addr(&gem_obj->vma_node);
 
 	drm_gem_object_unreference(gem_obj);
 
@@ -301,12 +296,11 @@  void drm_gem_cma_describe(struct drm_gem_cma_object *cma_obj, struct seq_file *m
 {
 	struct drm_gem_object *obj = &cma_obj->base;
 	struct drm_device *dev = obj->dev;
-	uint64_t off = 0;
+	uint64_t off;
 
 	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
 
-	if (obj->map_list.map)
-		off = (uint64_t)obj->map_list.hash.key;
+	off = drm_vma_node_start(&obj->vma_node);
 
 	seq_printf(m, "%2d (%2d) %08llx %08Zx %p %d",
 			obj->name, obj->refcount.refcount.counter,
diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index 24c22a8..be32db1 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -10,6 +10,7 @@ 
  */
 
 #include <drm/drmP.h>
+#include <drm/drm_vma_manager.h>
 
 #include <linux/shmem_fs.h>
 #include <drm/exynos_drm.h>
@@ -152,8 +153,7 @@  out:
 	exynos_drm_fini_buf(obj->dev, buf);
 	exynos_gem_obj->buffer = NULL;
 
-	if (obj->map_list.map)
-		drm_gem_free_mmap_offset(obj);
+	drm_gem_free_mmap_offset(obj);
 
 	/* release file pointer to gem object. */
 	drm_gem_object_release(obj);
@@ -703,13 +703,11 @@  int exynos_drm_gem_dumb_map_offset(struct drm_file *file_priv,
 		goto unlock;
 	}
 
-	if (!obj->map_list.map) {
-		ret = drm_gem_create_mmap_offset(obj);
-		if (ret)
-			goto out;
-	}
+	ret = drm_gem_create_mmap_offset(obj);
+	if (ret)
+		goto out;
 
-	*offset = (u64)obj->map_list.hash.key << PAGE_SHIFT;
+	*offset = drm_vma_node_offset_addr(&obj->vma_node);
 	DRM_DEBUG_KMS("offset = 0x%lx\n", (unsigned long)*offset);
 
 out:
diff --git a/drivers/gpu/drm/gma500/gem.c b/drivers/gpu/drm/gma500/gem.c
index fe1d332..2f77bea 100644
--- a/drivers/gpu/drm/gma500/gem.c
+++ b/drivers/gpu/drm/gma500/gem.c
@@ -26,6 +26,7 @@ 
 #include <drm/drmP.h>
 #include <drm/drm.h>
 #include <drm/gma_drm.h>
+#include <drm/drm_vma_manager.h>
 #include "psb_drv.h"
 
 int psb_gem_init_object(struct drm_gem_object *obj)
@@ -38,8 +39,7 @@  void psb_gem_free_object(struct drm_gem_object *obj)
 	struct gtt_range *gtt = container_of(obj, struct gtt_range, gem);
 
 	/* Remove the list map if one is present */
-	if (obj->map_list.map)
-		drm_gem_free_mmap_offset(obj);
+	drm_gem_free_mmap_offset(obj);
 	drm_gem_object_release(obj);
 
 	/* This must occur last as it frees up the memory of the GEM object */
@@ -81,13 +81,10 @@  int psb_gem_dumb_map_gtt(struct drm_file *file, struct drm_device *dev,
 	/* What validation is needed here ? */
 
 	/* Make it mmapable */
-	if (!obj->map_list.map) {
-		ret = drm_gem_create_mmap_offset(obj);
-		if (ret)
-			goto out;
-	}
-	/* GEM should really work out the hash offsets for us */
-	*offset = (u64)obj->map_list.hash.key << PAGE_SHIFT;
+	ret = drm_gem_create_mmap_offset(obj);
+	if (ret)
+		goto out;
+	*offset = drm_vma_node_offset_addr(&obj->vma_node);
 out:
 	drm_gem_object_unreference(obj);
 unlock:
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 46bf7e3..53f81b3 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -26,6 +26,7 @@ 
  */
 
 #include <drm/drmP.h>
+#include <drm/drm_vma_manager.h>
 #include <drm/i915_drm.h>
 #include "i915_drv.h"
 #include "i915_trace.h"
@@ -1428,7 +1429,7 @@  i915_gem_release_mmap(struct drm_i915_gem_object *obj)
 
 	if (obj->base.dev->dev_mapping)
 		unmap_mapping_range(obj->base.dev->dev_mapping,
-				    (loff_t)obj->base.map_list.hash.key<<PAGE_SHIFT,
+				    (loff_t)drm_vma_node_offset_addr(&obj->base.vma_node),
 				    obj->base.size, 1);
 
 	obj->fault_mappable = false;
@@ -1486,7 +1487,7 @@  static int i915_gem_object_create_mmap_offset(struct drm_i915_gem_object *obj)
 	struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
 	int ret;
 
-	if (obj->base.map_list.map)
+	if (drm_vma_node_has_offset(&obj->base.vma_node))
 		return 0;
 
 	dev_priv->mm.shrinker_no_lock_stealing = true;
@@ -1517,9 +1518,6 @@  out:
 
 static void i915_gem_object_free_mmap_offset(struct drm_i915_gem_object *obj)
 {
-	if (!obj->base.map_list.map)
-		return;
-
 	drm_gem_free_mmap_offset(&obj->base);
 }
 
@@ -1558,7 +1556,7 @@  i915_gem_mmap_gtt(struct drm_file *file,
 	if (ret)
 		goto out;
 
-	*offset = (u64)obj->base.map_list.hash.key << PAGE_SHIFT;
+	*offset = drm_vma_node_offset_addr(&obj->base.vma_node);
 
 out:
 	drm_gem_object_unreference(&obj->base);
diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
index cbcd71e..f90531fc00 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem.c
@@ -20,6 +20,7 @@ 
 
 #include <linux/spinlock.h>
 #include <linux/shmem_fs.h>
+#include <drm/drm_vma_manager.h>
 
 #include "omap_drv.h"
 #include "omap_dmm_tiler.h"
@@ -308,21 +309,20 @@  uint32_t omap_gem_flags(struct drm_gem_object *obj)
 static uint64_t mmap_offset(struct drm_gem_object *obj)
 {
 	struct drm_device *dev = obj->dev;
+	int ret;
+	size_t size;
 
 	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
 
-	if (!obj->map_list.map) {
-		/* Make it mmapable */
-		size_t size = omap_gem_mmap_size(obj);
-		int ret = _drm_gem_create_mmap_offset_size(obj, size);
-
-		if (ret) {
-			dev_err(dev->dev, "could not allocate mmap offset\n");
-			return 0;
-		}
+	/* Make it mmapable */
+	size = omap_gem_mmap_size(obj);
+	ret = _drm_gem_create_mmap_offset_size(obj, size);
+	if (ret) {
+		dev_err(dev->dev, "could not allocate mmap offset\n");
+		return 0;
 	}
 
-	return (uint64_t)obj->map_list.hash.key << PAGE_SHIFT;
+	return drm_vma_node_offset_addr(&obj->vma_node);
 }
 
 uint64_t omap_gem_mmap_offset(struct drm_gem_object *obj)
@@ -997,12 +997,11 @@  void omap_gem_describe(struct drm_gem_object *obj, struct seq_file *m)
 {
 	struct drm_device *dev = obj->dev;
 	struct omap_gem_object *omap_obj = to_omap_bo(obj);
-	uint64_t off = 0;
+	uint64_t off;
 
 	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
 
-	if (obj->map_list.map)
-		off = (uint64_t)obj->map_list.hash.key;
+	off = drm_vma_node_start(&obj->vma_node);
 
 	seq_printf(m, "%08x: %2d (%2d) %08llx %08Zx (%2d) %p %4d",
 			omap_obj->flags, obj->name, obj->refcount.refcount.counter,
@@ -1309,8 +1308,7 @@  void omap_gem_free_object(struct drm_gem_object *obj)
 
 	list_del(&omap_obj->mm_list);
 
-	if (obj->map_list.map)
-		drm_gem_free_mmap_offset(obj);
+	drm_gem_free_mmap_offset(obj);
 
 	/* this means the object is still pinned.. which really should
 	 * not happen.  I think..
diff --git a/drivers/gpu/drm/omapdrm/omap_gem_helpers.c b/drivers/gpu/drm/omapdrm/omap_gem_helpers.c
index f9eb679..dbb1575 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem_helpers.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem_helpers.c
@@ -118,52 +118,7 @@  _drm_gem_create_mmap_offset_size(struct drm_gem_object *obj, size_t size)
 {
 	struct drm_device *dev = obj->dev;
 	struct drm_gem_mm *mm = dev->mm_private;
-	struct drm_map_list *list;
-	struct drm_local_map *map;
-	int ret = 0;
-
-	/* Set the object up for mmap'ing */
-	list = &obj->map_list;
-	list->map = kzalloc(sizeof(struct drm_map_list), GFP_KERNEL);
-	if (!list->map)
-		return -ENOMEM;
-
-	map = list->map;
-	map->type = _DRM_GEM;
-	map->size = size;
-	map->handle = obj;
-
-	/* Get a DRM GEM mmap offset allocated... */
-	list->file_offset_node = drm_mm_search_free(&mm->offset_manager,
-			size / PAGE_SIZE, 0, 0);
-
-	if (!list->file_offset_node) {
-		DRM_ERROR("failed to allocate offset for bo %d\n", obj->name);
-		ret = -ENOSPC;
-		goto out_free_list;
-	}
-
-	list->file_offset_node = drm_mm_get_block(list->file_offset_node,
-			size / PAGE_SIZE, 0);
-	if (!list->file_offset_node) {
-		ret = -ENOMEM;
-		goto out_free_list;
-	}
-
-	list->hash.key = list->file_offset_node->start;
-	ret = drm_ht_insert_item(&mm->offset_hash, &list->hash);
-	if (ret) {
-		DRM_ERROR("failed to add to map hash\n");
-		goto out_free_mm;
-	}
-
-	return 0;
-
-out_free_mm:
-	drm_mm_put_block(list->file_offset_node);
-out_free_list:
-	kfree(list->map);
-	list->map = NULL;
 
-	return ret;
+	return drm_vma_offset_add(&mm->vma_manager, &obj->vma_node,
+				  size / PAGE_SIZE);
 }
diff --git a/drivers/gpu/drm/udl/udl_gem.c b/drivers/gpu/drm/udl/udl_gem.c
index ef034fa..2a4cb2f 100644
--- a/drivers/gpu/drm/udl/udl_gem.c
+++ b/drivers/gpu/drm/udl/udl_gem.c
@@ -223,8 +223,7 @@  void udl_gem_free_object(struct drm_gem_object *gem_obj)
 	if (obj->pages)
 		udl_gem_put_pages(obj);
 
-	if (gem_obj->map_list.map)
-		drm_gem_free_mmap_offset(gem_obj);
+	drm_gem_free_mmap_offset(gem_obj);
 }
 
 /* the dumb interface doesn't work with the GEM straight MMAP
@@ -247,13 +246,11 @@  int udl_gem_mmap(struct drm_file *file, struct drm_device *dev,
 	ret = udl_gem_get_pages(gobj, GFP_KERNEL);
 	if (ret)
 		goto out;
-	if (!gobj->base.map_list.map) {
-		ret = drm_gem_create_mmap_offset(obj);
-		if (ret)
-			goto out;
-	}
+	ret = drm_gem_create_mmap_offset(obj);
+	if (ret)
+		goto out;
 
-	*offset = (u64)gobj->base.map_list.hash.key << PAGE_SHIFT;
+	*offset = drm_vma_node_offset_addr(&gobj->base.vma_node);
 
 out:
 	drm_gem_object_unreference(&gobj->base);
diff --git a/drivers/gpu/host1x/drm/gem.c b/drivers/gpu/host1x/drm/gem.c
index c5e9a9b..bc323b3 100644
--- a/drivers/gpu/host1x/drm/gem.c
+++ b/drivers/gpu/host1x/drm/gem.c
@@ -108,7 +108,7 @@  static void tegra_bo_destroy(struct drm_device *drm, struct tegra_bo *bo)
 
 unsigned int tegra_bo_get_mmap_offset(struct tegra_bo *bo)
 {
-	return (unsigned int)bo->gem.map_list.hash.key << PAGE_SHIFT;
+	return (unsigned int)drm_vma_node_offset_addr(&bo->gem.vma_node);
 }
 
 struct tegra_bo *tegra_bo_create(struct drm_device *drm, unsigned int size)
@@ -182,8 +182,7 @@  void tegra_bo_free_object(struct drm_gem_object *gem)
 {
 	struct tegra_bo *bo = to_tegra_bo(gem);
 
-	if (gem->map_list.map)
-		drm_gem_free_mmap_offset(gem);
+	drm_gem_free_mmap_offset(gem);
 
 	drm_gem_object_release(gem);
 	tegra_bo_destroy(gem->dev, bo);
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 0ab6a09..4b518e0 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -71,6 +71,7 @@ 
 #include <asm/pgalloc.h>
 #include <drm/drm.h>
 #include <drm/drm_sarea.h>
+#include <drm/drm_vma_manager.h>
 
 #include <linux/idr.h>
 
@@ -587,7 +588,6 @@  struct drm_map_list {
 	struct drm_local_map *map;	/**< mapping */
 	uint64_t user_token;
 	struct drm_master *master;
-	struct drm_mm_node *file_offset_node;	/**< fake offset */
 };
 
 /**
@@ -622,8 +622,7 @@  struct drm_ati_pcigart_info {
  * GEM specific mm private for tracking GEM objects
  */
 struct drm_gem_mm {
-	struct drm_mm offset_manager;	/**< Offset mgmt for buffer objects */
-	struct drm_open_hash offset_hash; /**< User token hash table for maps */
+	struct drm_vma_offset_manager vma_manager;
 };
 
 /**
@@ -644,7 +643,7 @@  struct drm_gem_object {
 	struct file *filp;
 
 	/* Mapping info for this object */
-	struct drm_map_list map_list;
+	struct drm_vma_offset_node vma_node;
 
 	/**
 	 * Size of the object, in bytes.  Immutable over the object's
diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
index 238a166..272580c 100644
--- a/include/uapi/drm/drm.h
+++ b/include/uapi/drm/drm.h
@@ -181,7 +181,7 @@  enum drm_map_type {
 	_DRM_AGP = 3,		  /**< AGP/GART */
 	_DRM_SCATTER_GATHER = 4,  /**< Scatter/gather memory for PCI DMA */
 	_DRM_CONSISTENT = 5,	  /**< Consistent memory for PCI DMA */
-	_DRM_GEM = 6,		  /**< GEM object */
+	_DRM_GEM = 6,		  /**< GEM object (obsolete) */
 };
 
 /**