Added some boilerplate for the structs, documented members where they are relevant and plenty of markup for hyperlinks all over. And a few small wording polish.
Note that the intro needs some more love after the DRM_MM_INSERT_* patch from Chris has landed.
v2: Spelling fixes (Chris).
v3: Use &struct foo instead of &foo structure (Chris).
Cc: Chris Wilson chris@chris-wilson.co.uk Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Signed-off-by: Daniel Vetter daniel.vetter@intel.com --- Documentation/gpu/drm-mm.rst | 2 +- drivers/gpu/drm/drm_mm.c | 41 +++++++++++---------- include/drm/drm_mm.h | 84 ++++++++++++++++++++++++++++++++++---------- 3 files changed, 89 insertions(+), 38 deletions(-)
diff --git a/Documentation/gpu/drm-mm.rst b/Documentation/gpu/drm-mm.rst index cb5daffcd6be..5355e5ad51a7 100644 --- a/Documentation/gpu/drm-mm.rst +++ b/Documentation/gpu/drm-mm.rst @@ -442,7 +442,7 @@ LRU Scan/Eviction Support -------------------------
.. kernel-doc:: drivers/gpu/drm/drm_mm.c - :doc: lru scan roaster + :doc: lru scan roster
DRM MM Range Allocator Function References ------------------------------------------ diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c index e54aa3fa538f..229b3f525dee 100644 --- a/drivers/gpu/drm/drm_mm.c +++ b/drivers/gpu/drm/drm_mm.c @@ -59,8 +59,8 @@ * * 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 + * datastructures. drm_mm itself will not do any memory 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 @@ -78,7 +78,7 @@ * 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 + * supplied. Furthermore every &drm_mm_node has a color value (which is just an * opaque 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 @@ -296,11 +296,11 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_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. + * 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. All other + * fields must be cleared to 0. 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. @@ -375,7 +375,7 @@ EXPORT_SYMBOL(drm_mm_reserve_node); * @sflags: flags to fine-tune the allocation search * @aflags: flags to fine-tune the allocation behavior * - * The preallocated node must be cleared to 0. + * The preallocated @node must be cleared to 0. * * Returns: * 0 on success, -ENOSPC if there's no suitable hole. @@ -537,7 +537,7 @@ void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new) EXPORT_SYMBOL(drm_mm_replace_node);
/** - * DOC: lru scan roaster + * DOC: lru scan roster * * 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 @@ -549,9 +549,11 @@ EXPORT_SYMBOL(drm_mm_replace_node); * The DRM range allocator supports this use-case through the scanning * interfaces. First a scan operation needs to be initialized with * drm_mm_scan_init() or drm_mm_scan_init_with_range(). The driver adds - * objects to the roster (probably by walking an LRU list, but this can be - * freely implemented) (using drm_mm_scan_add_block()) until a suitable hole - * is found or there are no further evictable objects. + * objects to the roster, probably by walking an LRU list, but this can be + * freely implemented. Eviction candiates are added using + * drm_mm_scan_add_block() until a suitable hole is found or there are no + * further evictable objects. Eviction roster metadata is tracked in struct + * &drm_mm_scan. * * 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 @@ -559,7 +561,7 @@ EXPORT_SYMBOL(drm_mm_replace_node); * * Finally the driver evicts all objects selected (drm_mm_scan_remove_block() * reported true) in the scan, and any overlapping nodes after color adjustment - * (drm_mm_scan_evict_color()). Adding and removing an object is O(1), and + * (drm_mm_scan_color_evict()). 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 @@ -705,14 +707,15 @@ EXPORT_SYMBOL(drm_mm_scan_add_block); * @scan: the active drm_mm scanner * @node: drm_mm_node to remove * - * Nodes _must_ be removed in exactly the reverse order from the scan list as - * they have been added (e.g. using list_add as they are added and then - * list_for_each over that eviction list to remove), otherwise the internal + * Nodes **must** be removed in exactly the reverse order from the scan list as + * they have been added (e.g. using list_add() as they are added and then + * list_for_each() over that eviction list to remove), 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). + * immediately following drm_mm_insert_node_in_range_generic() or one of the + * simpler versions of that function with !DRM_MM_SEARCH_BEST will then return + * the just freed block (because its at the top of the free_stack list). * * Returns: * True if this block should be evicted, false otherwise. Will always diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h index 1383ac2328b8..3bddca8fd2b5 100644 --- a/include/drm/drm_mm.h +++ b/include/drm/drm_mm.h @@ -67,16 +67,29 @@ enum drm_mm_allocator_flags { #define DRM_MM_BOTTOMUP DRM_MM_SEARCH_DEFAULT, DRM_MM_CREATE_DEFAULT #define DRM_MM_TOPDOWN DRM_MM_SEARCH_BELOW, DRM_MM_CREATE_TOP
+/** + * struct drm_mm_node - allocated block in the DRM allocator + * + * This represents an allocated block in a &drm_mm allocator. Except for + * pre-reserved nodes inserted using drm_mm_reserve_node() the structure is + * entirely opaque and should only be accessed through the provided funcions. + * Since allocation of these nodes is entirely handled by the driver they can be + * embedded. + */ struct drm_mm_node { + /** @color: Opaque driver-private tag. */ + unsigned long color; + /** @start: Start address of the allocated block. */ + u64 start; + /** @size: Size of the allocated block. */ + u64 size; + /* private: */ struct list_head node_list; struct list_head hole_stack; struct rb_node rb; unsigned hole_follows : 1; unsigned allocated : 1; bool scanned_block : 1; - unsigned long color; - u64 start; - u64 size; u64 __subtree_last; struct drm_mm *mm; #ifdef CONFIG_DRM_DEBUG_MM @@ -84,7 +97,29 @@ struct drm_mm_node { #endif };
+/** + * struct drm_mm - DRM allocator + * + * DRM range allocator with a few special functions and features geared towards + * managing GPU memory. Except for the @color_adjust callback the structure is + * entirely opaque and should only be accessed through the provided functions + * and macros. This structure can be embedded into larger driver structures. + */ struct drm_mm { + /** + * @color_adjust: + * + * Optional driver callback to further apply restrictions on a hole. The + * node argument points at the node containing the hole from which the + * block would be allocated (see drm_mm_hole_follows() and friends). The + * other arguments are the size of the block to be allocated. The driver + * can adjust the start and end as needed to e.g. insert guard pages. + */ + void (*color_adjust)(const struct drm_mm_node *node, + unsigned long color, + u64 *start, u64 *end); + + /* private: */ /* List of all memory nodes that immediately precede a free hole. */ struct list_head hole_stack; /* head_node.node_list is the list of all memory nodes, ordered @@ -93,14 +128,20 @@ struct drm_mm { /* Keep an interval_tree for fast lookup of drm_mm_nodes by address. */ struct rb_root interval_tree;
- void (*color_adjust)(const struct drm_mm_node *node, - unsigned long color, - u64 *start, u64 *end); - unsigned long scan_active; };
+/** + * struct drm_mm_scan - DRM allocator eviction roaster data + * + * This structure tracks data needed for the eviction roaster set up using + * drm_mm_scan_init(), and used with drm_mm_scan_add_block() and + * drm_mm_scan_remove_block(). The structure is entirely opaque and should only + * be accessed through the provided functions and macros. It is meant to be + * allocated temporarily by the driver on the stack. + */ struct drm_mm_scan { + /* private: */ struct drm_mm *mm;
u64 size; @@ -159,7 +200,8 @@ static inline bool drm_mm_initialized(const struct drm_mm *mm) * * Holes are embedded into the drm_mm using the tail of a drm_mm_node. * If you wish to know whether a hole follows this particular node, - * query this function. + * query this function. See also drm_mm_hole_node_start() and + * drm_mm_hole_node_end(). * * Returns: * True if a hole follows the @node. @@ -228,23 +270,23 @@ static inline u64 drm_mm_hole_node_end(const struct drm_mm_node *hole_node)
/** * drm_mm_for_each_node - iterator to walk over all allocated nodes - * @entry: drm_mm_node structure to assign to in each iteration step - * @mm: drm_mm allocator to walk + * @entry: &struct drm_mm_node to assign to in each iteration step + * @mm: &drm_mm allocator to walk * * This iterator walks over all nodes in the range allocator. It is implemented - * with list_for_each, so not save against removal of elements. + * with list_for_each(), so not save against removal of elements. */ #define drm_mm_for_each_node(entry, mm) \ list_for_each_entry(entry, drm_mm_nodes(mm), node_list)
/** * drm_mm_for_each_node_safe - iterator to walk over all allocated nodes - * @entry: drm_mm_node structure to assign to in each iteration step - * @next: drm_mm_node structure to store the next step - * @mm: drm_mm allocator to walk + * @entry: &struct drm_mm_node to assign to in each iteration step + * @next: &struct drm_mm_node to store the next step + * @mm: &drm_mm allocator to walk * * This iterator walks over all nodes in the range allocator. It is implemented - * with list_for_each_safe, so save against removal of elements. + * with list_for_each_safe(), so save against removal of elements. */ #define drm_mm_for_each_node_safe(entry, next, mm) \ list_for_each_entry_safe(entry, next, drm_mm_nodes(mm), node_list) @@ -259,13 +301,13 @@ static inline u64 drm_mm_hole_node_end(const struct drm_mm_node *hole_node)
/** * drm_mm_for_each_hole - iterator to walk over all holes - * @entry: drm_mm_node used internally to track progress - * @mm: drm_mm allocator to walk + * @entry: &drm_mm_node used internally to track progress + * @mm: &drm_mm allocator to walk * @hole_start: ulong variable to assign the hole start to on each iteration * @hole_end: ulong variable to assign the hole end to on each iteration * * This iterator walks over all holes in the range allocator. It is implemented - * with list_for_each, so not save against removal of elements. @entry is used + * with list_for_each(), so not save against removal of elements. @entry is used * internally and will not reflect a real drm_mm_node for the very first hole. * Hence users of this iterator may not access it. * @@ -334,6 +376,9 @@ static inline int drm_mm_insert_node_in_range(struct drm_mm *mm, * @sflags: flags to fine-tune the allocation search * @aflags: flags to fine-tune the allocation behavior * + * This is a simplified version of drm_mm_insert_node_in_range_generic() with no + * range restrictions applied. + * * The preallocated node must be cleared to 0. * * Returns: @@ -434,6 +479,9 @@ void drm_mm_scan_init_with_range(struct drm_mm_scan *scan, * @color: opaque tag value to use for the allocation * @flags: flags to specify how the allocation will be performed afterwards * + * This is a simplified version of drm_mm_scan_init_with_range() with no range + * restrictions applied. + * * This simply sets up the scanning routines with the parameters for the desired * hole. *