WebSVN – Kolibri OS – Diff – /drivers/video/drm/drm_mm.c

 /**************************************************************************
+ *
  * Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND., USA.
  * All Rights Reserved.
+ *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the
  * "Software"), to deal in the Software without restriction, including
  * without limitation the rights to use, copy, modify, merge, publish,
  * distribute, sub license, and/or sell copies of the Software, and to
  * permit persons to whom the Software is furnished to do so, subject to
  * the following conditions:
+ *
  * The above copyright notice and this permission notice (including the
  * next paragraph) shall be included in all copies or substantial portions
  * of the Software.
+ *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  * USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ *
  **************************************************************************/
 /*
  * Generic simple memory manager implementation. Intended to be used as a base
  * class implementation for more advanced memory managers.
+ *
  * Note that the algorithm used is quite simple and there might be substantial
  * performance gains if a smarter free list is implemented. Currently it is just an
  * unordered stack of free regions. This could easily be improved if an RB-tree
  * is used instead. At least if we expect heavy fragmentation.
+ *
  * Aligned allocations can also see improvement.
+ *
  * Authors:
  * Thomas Hellström
  */
 #include
 #include
 #include
 #include
 #include
+/**
+ * DOC: Overview
+ *
+ * drm_mm provides a simple range allocator. The drivers are free to use the
+ * resource allocator from the linux core if it suits them, the upside of drm_mm
+ * is that it's in the DRM core. Which means that it's easier to extend for
+ * some of the crazier special purpose needs of gpus.
+ *
+ * The main data struct is &drm_mm, allocations are tracked in &drm_mm_node.
+ * Drivers are free to embed either of them into their own suitable
+ * datastructures. drm_mm itself will not do any allocations of its own, so if
+ * drivers choose not to embed nodes they need to still allocate them
+ * themselves.
+ *
+ * The range allocator also supports reservation of preallocated blocks. This is
+ * useful for taking over initial mode setting configurations from the firmware,
+ * where an object needs to be created which exactly matches the firmware's
+ * scanout target. As long as the range is still free it can be inserted anytime
+ * after the allocator is initialized, which helps with avoiding looped
+ * depencies in the driver load sequence.
+ *
+ * drm_mm maintains a stack of most recently freed holes, which of all
+ * simplistic datastructures seems to be a fairly decent approach to clustering
+ * allocations and avoiding too much fragmentation. This means free space
+ * searches are O(num_holes). Given that all the fancy features drm_mm supports
+ * something better would be fairly complex and since gfx thrashing is a fairly
+ * steep cliff not a real concern. Removing a node again is O(1).
+ *
+ * drm_mm supports a few features: Alignment and range restrictions can be
+ * supplied. Further more every &drm_mm_node has a color value (which is just an
+ * opaqua unsigned long) which in conjunction with a driver callback can be used
+ * to implement sophisticated placement restrictions. The i915 DRM driver uses
+ * this to implement guard pages between incompatible caching domains in the
+ * graphics TT.
+ *
+ * Two behaviors are supported for searching and allocating: bottom-up and top-down.
+ * The default is bottom-up. Top-down allocation can be used if the memory area
+ * has different restrictions, or just to reduce fragmentation.
+ *
+ * Finally iteration helpers to walk all nodes and all holes are provided as are
+ * some basic allocator dumpers for debugging.
-#define MM_UNUSED_TARGET 4
+ */
 static struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
 						unsigned long size,
 						unsigned alignment,
 						unsigned long color,
 						enum drm_mm_search_flags flags);
 static struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
 						unsigned long size,
 						unsigned alignment,
 						unsigned long color,
 						unsigned long start,
 						unsigned long end,
 						enum drm_mm_search_flags flags);
 static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
 				 struct drm_mm_node *node,
 				 unsigned long size, unsigned alignment,
-				 unsigned long color)
+				 unsigned long color,
+				 enum drm_mm_allocator_flags flags)
+{
 	struct drm_mm *mm = hole_node->mm;
 	unsigned long hole_start = drm_mm_hole_node_start(hole_node);
 	unsigned long hole_end = drm_mm_hole_node_end(hole_node);
 	unsigned long adj_start = hole_start;
 	unsigned long adj_end = hole_end;
 	BUG_ON(node->allocated);
 	if (mm->color_adjust)
 		mm->color_adjust(hole_node, color, &adj_start, &adj_end);
+	if (flags & DRM_MM_CREATE_TOP)
+		adj_start = adj_end - size;
 	if (alignment) {
 		unsigned tmp = adj_start % alignment;
+		if (tmp) {
+			if (flags & DRM_MM_CREATE_TOP)
+				adj_start -= tmp;
-		if (tmp)
+			else
 			adj_start += alignment - tmp;
+	}
+	}
+	BUG_ON(adj_start < hole_start);
 	BUG_ON(adj_end > hole_end);
 	if (adj_start == hole_start) {
 		hole_node->hole_follows = 0;
 		list_del(&hole_node->hole_stack);
+	}
 	node->start = adj_start;
 	node->size = size;
 	node->mm = mm;
 	node->color = color;
 	node->allocated = 1;
 	INIT_LIST_HEAD(&node->hole_stack);
 	list_add(&node->node_list, &hole_node->node_list);
 	BUG_ON(node->start + node->size > adj_end);
 	node->hole_follows = 0;
 	if (__drm_mm_hole_node_start(node) < hole_end) {
 		list_add(&node->hole_stack, &mm->hole_stack);
 		node->hole_follows = 1;
+	}
+}
+/**
+ * drm_mm_reserve_node - insert an pre-initialized node
+ * @mm: drm_mm allocator to insert @node into
+ * @node: drm_mm_node to insert
+ *
+ * This functions inserts an already set-up drm_mm_node into the allocator,
+ * meaning that start, size and color must be set by the caller. This is useful
+ * to initialize the allocator with preallocated objects which must be set-up
+ * before the range allocator can be set-up, e.g. when taking over a firmware
+ * framebuffer.
+ *
+ * Returns:
+ * 0 on success, -ENOSPC if there's no hole where @node is.
  */
 int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node)
+{
 	struct drm_mm_node *hole;
 	unsigned long end = node->start + node->size;
 	unsigned long hole_start;
 	unsigned long hole_end;
 	BUG_ON(node == NULL);
 	/* Find the relevant hole to add our node to */
 	drm_mm_for_each_hole(hole, mm, hole_start, hole_end) {
 		if (hole_start > node->start || hole_end < end)
 			continue;
 		node->mm = mm;
 		node->allocated = 1;
 		INIT_LIST_HEAD(&node->hole_stack);
 		list_add(&node->node_list, &hole->node_list);
 		if (node->start == hole_start) {
 			hole->hole_follows = 0;
 			list_del_init(&hole->hole_stack);
+		}
 		node->hole_follows = 0;
 		if (end != hole_end) {
 			list_add(&node->hole_stack, &mm->hole_stack);
 			node->hole_follows = 1;
+		}
 		return 0;
+	}
-	WARN(1, "no hole found for node 0x%lx + 0x%lx\n",
 	     node->start, node->size);
 	return -ENOSPC;
+}
 EXPORT_SYMBOL(drm_mm_reserve_node);
 /**
+ * drm_mm_insert_node_generic - search for space and insert @node
+ * @mm: drm_mm to allocate from
+ * @node: preallocate node to insert
+ * @size: size of the allocation
+ * @alignment: alignment of the allocation
+ * @color: opaque tag value to use for this node
- * Search for free space and insert a preallocated memory node. Returns
+ * @sflags: flags to fine-tune the allocation search
- * -ENOSPC if no suitable free area is available. The preallocated memory node
+ * @aflags: flags to fine-tune the allocation behavior
+ *
- * must be cleared.
+ * The preallocated node must be cleared to 0.
+ *
+ * Returns:
+ * 0 on success, -ENOSPC if there's no suitable hole.
  */
 int drm_mm_insert_node_generic(struct drm_mm *mm, struct drm_mm_node *node,
 			       unsigned long size, unsigned alignment,
 			       unsigned long color,
-			       enum drm_mm_search_flags flags)
+			       enum drm_mm_search_flags sflags,
+			       enum drm_mm_allocator_flags aflags)
+{
 	struct drm_mm_node *hole_node;
 	hole_node = drm_mm_search_free_generic(mm, size, alignment,
-					       color, flags);
+					       color, sflags);
 	if (!hole_node)
 		return -ENOSPC;
-	drm_mm_insert_helper(hole_node, node, size, alignment, color);
+	drm_mm_insert_helper(hole_node, node, size, alignment, color, aflags);
 	return 0;
+}
 EXPORT_SYMBOL(drm_mm_insert_node_generic);
 static void drm_mm_insert_helper_range(struct drm_mm_node *hole_node,
 				       struct drm_mm_node *node,
 				       unsigned long size, unsigned alignment,
 				       unsigned long color,
-				       unsigned long start, unsigned long end)
+				       unsigned long start, unsigned long end,
+				       enum drm_mm_allocator_flags flags)
+{
 	struct drm_mm *mm = hole_node->mm;
 	unsigned long hole_start = drm_mm_hole_node_start(hole_node);
 	unsigned long hole_end = drm_mm_hole_node_end(hole_node);
 	unsigned long adj_start = hole_start;
 	unsigned long adj_end = hole_end;
 	BUG_ON(!hole_node->hole_follows || node->allocated);
 	if (adj_start < start)
 		adj_start = start;
 	if (adj_end > end)
 		adj_end = end;
+	if (flags & DRM_MM_CREATE_TOP)
+		adj_start = adj_end - size;
 	if (mm->color_adjust)
 		mm->color_adjust(hole_node, color, &adj_start, &adj_end);
 	if (alignment) {
 		unsigned tmp = adj_start % alignment;
-	if (tmp)
+		if (tmp) {
+			if (flags & DRM_MM_CREATE_TOP)
+				adj_start -= tmp;
+			else
 			adj_start += alignment - tmp;
+	}
+	}
 	if (adj_start == hole_start) {
 		hole_node->hole_follows = 0;
 		list_del(&hole_node->hole_stack);
+	}
 	node->start = adj_start;
 	node->size = size;
 	node->mm = mm;
 	node->color = color;
 	node->allocated = 1;
 	INIT_LIST_HEAD(&node->hole_stack);
 	list_add(&node->node_list, &hole_node->node_list);
+	BUG_ON(node->start < start);
 	BUG_ON(node->start < adj_start);
 	BUG_ON(node->start + node->size > adj_end);
 	BUG_ON(node->start + node->size > end);
 	node->hole_follows = 0;
 	if (__drm_mm_hole_node_start(node) < hole_end) {
 		list_add(&node->hole_stack, &mm->hole_stack);
 		node->hole_follows = 1;
+	}
+}
 /**
+ * drm_mm_insert_node_in_range_generic - ranged search for space and insert @node
+ * @mm: drm_mm to allocate from
+ * @node: preallocate node to insert
+ * @size: size of the allocation
+ * @alignment: alignment of the allocation
+ * @color: opaque tag value to use for this node
+ * @start: start of the allowed range for this node
+ * @end: end of the allowed range for this node
- * Search for free space and insert a preallocated memory node. Returns
+ * @sflags: flags to fine-tune the allocation search
- * -ENOSPC if no suitable free area is available. This is for range
+ * @aflags: flags to fine-tune the allocation behavior
+ *
- * restricted allocations. The preallocated memory node must be cleared.
+ * The preallocated node must be cleared to 0.
+ *
+ * Returns:
+ * 0 on success, -ENOSPC if there's no suitable hole.
  */
 int drm_mm_insert_node_in_range_generic(struct drm_mm *mm, struct drm_mm_node *node,
-					unsigned long size, unsigned alignment, unsigned long color,
+					unsigned long size, unsigned alignment,
+					unsigned long color,
 					unsigned long start, unsigned long end,
-					enum drm_mm_search_flags flags)
+					enum drm_mm_search_flags sflags,
+					enum drm_mm_allocator_flags aflags)
+{
 	struct drm_mm_node *hole_node;
 	hole_node = drm_mm_search_free_in_range_generic(mm,
 							size, alignment, color,
-							start, end, flags);
+							start, end, sflags);
 	if (!hole_node)
 		return -ENOSPC;
 	drm_mm_insert_helper_range(hole_node, node,
 				   size, alignment, color,
-				   start, end);
+				   start, end, aflags);
 	return 0;
+}
 EXPORT_SYMBOL(drm_mm_insert_node_in_range_generic);
 /**
- * Remove a memory node from the allocator.
+ * drm_mm_remove_node - Remove a memory node from the allocator.
+ * @node: drm_mm_node to remove
+ *
+ * This just removes a node from its drm_mm allocator. The node does not need to
+ * be cleared again before it can be re-inserted into this or any other drm_mm
+ * allocator. It is a bug to call this function on a un-allocated node.
  */
 void drm_mm_remove_node(struct drm_mm_node *node)
+{
 	struct drm_mm *mm = node->mm;
 	struct drm_mm_node *prev_node;
 	if (WARN_ON(!node->allocated))
 		return;
 	BUG_ON(node->scanned_block || node->scanned_prev_free
 				   || node->scanned_next_free);
 	prev_node =
 	    list_entry(node->node_list.prev, struct drm_mm_node, node_list);
 	if (node->hole_follows) {
 		BUG_ON(__drm_mm_hole_node_start(node) ==
 		       __drm_mm_hole_node_end(node));
 		list_del(&node->hole_stack);
 	} else
 		BUG_ON(__drm_mm_hole_node_start(node) !=
 		       __drm_mm_hole_node_end(node));
 	if (!prev_node->hole_follows) {
 		prev_node->hole_follows = 1;
 		list_add(&prev_node->hole_stack, &mm->hole_stack);
 				} else
 		list_move(&prev_node->hole_stack, &mm->hole_stack);
 	list_del(&node->node_list);
 	node->allocated = 0;
+}
 EXPORT_SYMBOL(drm_mm_remove_node);
 static int check_free_hole(unsigned long start, unsigned long end,
 			   unsigned long size, unsigned alignment)
+{
 	if (end - start < size)
 		return 0;
 	if (alignment) {
 		unsigned tmp = start % alignment;
 		if (tmp)
 			start += alignment - tmp;
+	}
 	return end >= start + size;
+}
 static struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
 				       unsigned long size,
 					       unsigned alignment,
 					       unsigned long color,
 						      enum drm_mm_search_flags flags)
+{
 	struct drm_mm_node *entry;
 	struct drm_mm_node *best;
 	unsigned long adj_start;
 	unsigned long adj_end;
 	unsigned long best_size;
 	BUG_ON(mm->scanned_blocks);
 	best = NULL;
 	best_size = ~0UL;
+	__drm_mm_for_each_hole(entry, mm, adj_start, adj_end,
+			       flags & DRM_MM_SEARCH_BELOW) {
+		unsigned long hole_size = adj_end - adj_start;
 	drm_mm_for_each_hole(entry, mm, adj_start, adj_end) {
 		if (mm->color_adjust) {
 			mm->color_adjust(entry, color, &adj_start, &adj_end);
 			if (adj_end <= adj_start)
 				continue;
+		}
 		if (!check_free_hole(adj_start, adj_end, size, alignment))
 			continue;
 		if (!(flags & DRM_MM_SEARCH_BEST))
 				return entry;
-			if (entry->size < best_size) {
+		if (hole_size < best_size) {
 				best = entry;
-				best_size = entry->size;
+			best_size = hole_size;
+			}
+		}
 	return best;
+}
 static struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
 						unsigned long size,
 						unsigned alignment,
 							unsigned long color,
 						unsigned long start,
 						unsigned long end,
 							enum drm_mm_search_flags flags)
+{
 	struct drm_mm_node *entry;
 	struct drm_mm_node *best;
 	unsigned long adj_start;
 	unsigned long adj_end;
 	unsigned long best_size;
 	BUG_ON(mm->scanned_blocks);
 	best = NULL;
 	best_size = ~0UL;
+	__drm_mm_for_each_hole(entry, mm, adj_start, adj_end,
+			       flags & DRM_MM_SEARCH_BELOW) {
+		unsigned long hole_size = adj_end - adj_start;
 	drm_mm_for_each_hole(entry, mm, adj_start, adj_end) {
 		if (adj_start < start)
 			adj_start = start;
 		if (adj_end > end)
 			adj_end = end;
 		if (mm->color_adjust) {
 			mm->color_adjust(entry, color, &adj_start, &adj_end);
 			if (adj_end <= adj_start)
 				continue;
+		}
 		if (!check_free_hole(adj_start, adj_end, size, alignment))
 			continue;
 		if (!(flags & DRM_MM_SEARCH_BEST))
 				return entry;
-			if (entry->size < best_size) {
+		if (hole_size < best_size) {
 				best = entry;
-				best_size = entry->size;
+			best_size = hole_size;
+			}
+		}
 	return best;
+}
 /**
+ * drm_mm_replace_node - move an allocation from @old to @new
+ * @old: drm_mm_node to remove from the allocator
+ * @new: drm_mm_node which should inherit @old's allocation
+ *
+ * This is useful for when drivers embed the drm_mm_node structure and hence
- * Moves an allocation. To be used with embedded struct drm_mm_node.
+ * can't move allocations by reassigning pointers. It's a combination of remove
+ * and insert with the guarantee that the allocation start will match.
  */
 void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new)
+{
 	list_replace(&old->node_list, &new->node_list);
 	list_replace(&old->hole_stack, &new->hole_stack);
 	new->hole_follows = old->hole_follows;
 	new->mm = old->mm;
 	new->start = old->start;
 	new->size = old->size;
 	new->color = old->color;
 	old->allocated = 0;
 	new->allocated = 1;
+}
 EXPORT_SYMBOL(drm_mm_replace_node);
 /**
+ * DOC: lru scan roaster
+ *
+ * Very often GPUs need to have continuous allocations for a given object. When
+ * evicting objects to make space for a new one it is therefore not most
+ * efficient when we simply start to select all objects from the tail of an LRU
+ * until there's a suitable hole: Especially for big objects or nodes that
+ * otherwise have special allocation constraints there's a good chance we evict
+ * lots of (smaller) objects unecessarily.
+ *
+ * The DRM range allocator supports this use-case through the scanning
+ * interfaces. First a scan operation needs to be initialized with
+ * drm_mm_init_scan() or drm_mm_init_scan_with_range(). The the driver adds
+ * objects to the roaster (probably by walking an LRU list, but this can be
+ * freely implemented) until a suitable hole is found or there's no further
+ * evitable object.
+ *
+ * The the driver must walk through all objects again in exactly the reverse
+ * order to restore the allocator state. Note that while the allocator is used
+ * in the scan mode no other operation is allowed.
+ *
+ * Finally the driver evicts all objects selected in the scan. Adding and
+ * removing an object is O(1), and since freeing a node is also O(1) the overall
+ * complexity is O(scanned_objects). So like the free stack which needs to be
+ * walked before a scan operation even begins this is linear in the number of
+ * objects. It doesn't seem to hurt badly.
+ */
+/**
- * Initializa lru scanning.
+ * drm_mm_init_scan - initialize lru scanning
+ * @mm: drm_mm to scan
+ * @size: size of the allocation
+ * @alignment: alignment of the allocation
+ * @color: opaque tag value to use for the allocation
+ *
  * This simply sets up the scanning routines with the parameters for the desired
+ * hole. Note that there's no need to specify allocation flags, since they only
- * hole.
+ * change the place a node is allocated from within a suitable hole.
+ *
+ * Warning:
- * Warning: As long as the scan list is non-empty, no other operations than
+ * As long as the scan list is non-empty, no other operations than
  * adding/removing nodes to/from the scan list are allowed.
  */
 void drm_mm_init_scan(struct drm_mm *mm,
 		      unsigned long size,
 		      unsigned alignment,
 		      unsigned long color)
+{
 	mm->scan_color = color;
 	mm->scan_alignment = alignment;
 	mm->scan_size = size;
 	mm->scanned_blocks = 0;
 	mm->scan_hit_start = 0;
 	mm->scan_hit_end = 0;
 	mm->scan_check_range = 0;
 	mm->prev_scanned_node = NULL;
+}
 EXPORT_SYMBOL(drm_mm_init_scan);
 /**
+ * drm_mm_init_scan - initialize range-restricted lru scanning
- * Initializa lru scanning.
+ * @mm: drm_mm to scan
+ * @size: size of the allocation
+ * @alignment: alignment of the allocation
+ * @color: opaque tag value to use for the allocation
+ * @start: start of the allowed range for the allocation
+ * @end: end of the allowed range for the allocation
+ *
  * This simply sets up the scanning routines with the parameters for the desired
- * hole. This version is for range-restricted scans.
+ * hole. Note that there's no need to specify allocation flags, since they only
+ * change the place a node is allocated from within a suitable hole.
+ *
+ * Warning:
- * Warning: As long as the scan list is non-empty, no other operations than
+ * As long as the scan list is non-empty, no other operations than
  * adding/removing nodes to/from the scan list are allowed.
  */
 void drm_mm_init_scan_with_range(struct drm_mm *mm,
 				 unsigned long size,
 				 unsigned alignment,
 				 unsigned long color,
 				 unsigned long start,
 				 unsigned long end)
+{
 	mm->scan_color = color;
 	mm->scan_alignment = alignment;
 	mm->scan_size = size;
 	mm->scanned_blocks = 0;
 	mm->scan_hit_start = 0;
 	mm->scan_hit_end = 0;
 	mm->scan_start = start;
 	mm->scan_end = end;
 	mm->scan_check_range = 1;
 	mm->prev_scanned_node = NULL;
+}
 EXPORT_SYMBOL(drm_mm_init_scan_with_range);
 /**
+ * drm_mm_scan_add_block - add a node to the scan list
+ * @node: drm_mm_node to add
+ *
  * Add a node to the scan list that might be freed to make space for the desired
  * hole.
+ *
+ * Returns:
- * Returns non-zero, if a hole has been found, zero otherwise.
+ * True if a hole has been found, false otherwise.
  */
-int drm_mm_scan_add_block(struct drm_mm_node *node)
+bool drm_mm_scan_add_block(struct drm_mm_node *node)
+{
 	struct drm_mm *mm = node->mm;
 	struct drm_mm_node *prev_node;
 	unsigned long hole_start, hole_end;
 	unsigned long adj_start, adj_end;
 	mm->scanned_blocks++;
 	BUG_ON(node->scanned_block);
 	node->scanned_block = 1;
 		prev_node = list_entry(node->node_list.prev, struct drm_mm_node,
 				       node_list);
 	node->scanned_preceeds_hole = prev_node->hole_follows;
 	prev_node->hole_follows = 1;
 	list_del(&node->node_list);
 	node->node_list.prev = &prev_node->node_list;
 	node->node_list.next = &mm->prev_scanned_node->node_list;
 	mm->prev_scanned_node = node;
 	adj_start = hole_start = drm_mm_hole_node_start(prev_node);
 	adj_end = hole_end = drm_mm_hole_node_end(prev_node);
 	if (mm->scan_check_range) {
 		if (adj_start < mm->scan_start)
 			adj_start = mm->scan_start;
 		if (adj_end > mm->scan_end)
 			adj_end = mm->scan_end;
+	}
 	if (mm->color_adjust)
 		mm->color_adjust(prev_node, mm->scan_color,
 				 &adj_start, &adj_end);
 	if (check_free_hole(adj_start, adj_end,
 			    mm->scan_size, mm->scan_alignment)) {
 		mm->scan_hit_start = hole_start;
 		mm->scan_hit_end = hole_end;
-		return 1;
+		return true;
+	}
-	return 0;
+	return false;
+}
 EXPORT_SYMBOL(drm_mm_scan_add_block);
 /**
- * Remove a node from the scan list.
+ * drm_mm_scan_remove_block - remove a node from the scan list
+ * @node: drm_mm_node to remove
+ *
  * Nodes _must_ be removed in the exact same order from the scan list as they
  * have been added, otherwise the internal state of the memory manager will be
  * corrupted.
+ *
  * When the scan list is empty, the selected memory nodes can be freed. An
  * immediately following drm_mm_search_free with !DRM_MM_SEARCH_BEST will then
  * return the just freed block (because its at the top of the free_stack list).
+ *
+ * Returns:
- * Returns one if this block should be evicted, zero otherwise. Will always
+ * True if this block should be evicted, false otherwise. Will always
- * return zero when no hole has been found.
+ * return false when no hole has been found.
  */
-int drm_mm_scan_remove_block(struct drm_mm_node *node)
+bool drm_mm_scan_remove_block(struct drm_mm_node *node)
+{
 	struct drm_mm *mm = node->mm;
 	struct drm_mm_node *prev_node;
 	mm->scanned_blocks--;
 	BUG_ON(!node->scanned_block);
 	node->scanned_block = 0;
 	prev_node = list_entry(node->node_list.prev, struct drm_mm_node,
 			       node_list);
 	prev_node->hole_follows = node->scanned_preceeds_hole;
 	list_add(&node->node_list, &prev_node->node_list);
 	 return (drm_mm_hole_node_end(node) > mm->scan_hit_start &&
 		 node->start < mm->scan_hit_end);
+}
 EXPORT_SYMBOL(drm_mm_scan_remove_block);
+/**
+ * drm_mm_clean - checks whether an allocator is clean
+ * @mm: drm_mm allocator to check
+ *
+ * Returns:
+ * True if the allocator is completely free, false if there's still a node
+ * allocated in it.
+ */
-int drm_mm_clean(struct drm_mm * mm)
+bool drm_mm_clean(struct drm_mm * mm)
+{
 	struct list_head *head = &mm->head_node.node_list;
 	return (head->next->next == head);
+}
 EXPORT_SYMBOL(drm_mm_clean);
+/**
+ * drm_mm_init - initialize a drm-mm allocator
+ * @mm: the drm_mm structure to initialize
+ * @start: start of the range managed by @mm
+ * @size: end of the range managed by @mm
+ *
+ * Note that @mm must be cleared to 0 before calling this function.
  */
 void drm_mm_init(struct drm_mm * mm, unsigned long start, unsigned long size)
+{
 	INIT_LIST_HEAD(&mm->hole_stack);
 	mm->scanned_blocks = 0;
 	/* Clever trick to avoid a special case in the free hole tracking. */
 	INIT_LIST_HEAD(&mm->head_node.node_list);
 	INIT_LIST_HEAD(&mm->head_node.hole_stack);
 	mm->head_node.hole_follows = 1;
 	mm->head_node.scanned_block = 0;
 	mm->head_node.scanned_prev_free = 0;
 	mm->head_node.scanned_next_free = 0;
 	mm->head_node.mm = mm;
 	mm->head_node.start = start + size;
 	mm->head_node.size = start - mm->head_node.start;
 	list_add_tail(&mm->head_node.hole_stack, &mm->hole_stack);
 	mm->color_adjust = NULL;
+}
 EXPORT_SYMBOL(drm_mm_init);
+/**
+ * drm_mm_takedown - clean up a drm_mm allocator
+ * @mm: drm_mm allocator to clean up
+ *
+ * Note that it is a bug to call this function on an allocator which is not
+ * clean.
  */
 void drm_mm_takedown(struct drm_mm * mm)
+{
 	WARN(!list_empty(&mm->head_node.node_list),
 	     "Memory manager not clean during takedown.\n");
+}
 EXPORT_SYMBOL(drm_mm_takedown);
 static unsigned long drm_mm_debug_hole(struct drm_mm_node *entry,
 				       const char *prefix)
+{
 	unsigned long hole_start, hole_end, hole_size;
 	if (entry->hole_follows) {
 		hole_start = drm_mm_hole_node_start(entry);
 		hole_end = drm_mm_hole_node_end(entry);
 	hole_size = hole_end - hole_start;
 		printk(KERN_DEBUG "%s 0x%08lx-0x%08lx: %8lu: free\n",
 			prefix, hole_start, hole_end,
 			hole_size);
 		return hole_size;
+	}
 	return 0;
+}
+/**
+ * drm_mm_debug_table - dump allocator state to dmesg
+ * @mm: drm_mm allocator to dump
+ * @prefix: prefix to use for dumping to dmesg
  */
 void drm_mm_debug_table(struct drm_mm *mm, const char *prefix)
+{
 	struct drm_mm_node *entry;
 	unsigned long total_used = 0, total_free = 0, total = 0;
 	total_free += drm_mm_debug_hole(&mm->head_node, prefix);
 	drm_mm_for_each_node(entry, mm) {
 		printk(KERN_DEBUG "%s 0x%08lx-0x%08lx: %8lu: used\n",
 			prefix, entry->start, entry->start + entry->size,
 			entry->size);
 		total_used += entry->size;
 		total_free += drm_mm_debug_hole(entry, prefix);
+		}
 	total = total_free + total_used;
 	printk(KERN_DEBUG "%s total: %lu, used %lu free %lu\n", prefix, total,
 		total_used, total_free);
+}
 EXPORT_SYMBOL(drm_mm_debug_table);
 #if defined(CONFIG_DEBUG_FS)
 static unsigned long drm_mm_dump_hole(struct seq_file *m, struct drm_mm_node *entry)
+{
 	unsigned long hole_start, hole_end, hole_size;
 	if (entry->hole_follows) {
 		hole_start = drm_mm_hole_node_start(entry);
 		hole_end = drm_mm_hole_node_end(entry);
 	hole_size = hole_end - hole_start;
 		seq_printf(m, "0x%08lx-0x%08lx: 0x%08lx: free\n",
 				hole_start, hole_end, hole_size);
 		return hole_size;
+	}
 	return 0;
+}
+/**
+ * drm_mm_dump_table - dump allocator state to a seq_file
+ * @m: seq_file to dump to
+ * @mm: drm_mm allocator to dump
  */
 int drm_mm_dump_table(struct seq_file *m, struct drm_mm *mm)
+{
 	struct drm_mm_node *entry;
 	unsigned long total_used = 0, total_free = 0, total = 0;
 	total_free += drm_mm_dump_hole(m, &mm->head_node);
 	drm_mm_for_each_node(entry, mm) {
 		seq_printf(m, "0x%08lx-0x%08lx: 0x%08lx: used\n",
 				entry->start, entry->start + entry->size,
 				entry->size);
 		total_used += entry->size;
 		total_free += drm_mm_dump_hole(m, entry);
+		}
 	total = total_free + total_used;
 	seq_printf(m, "total: %lu, used %lu free %lu\n", total, total_used, total_free);
 	return 0;
+}
 EXPORT_SYMBOL(drm_mm_dump_table);
 #endif

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(root)/drivers/video/drm/drm_mm.c – Rev 4104 → 5060