drm/mm: Some doc polish
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> Reviewed-by: David Herrmann <dh.herrmann@gmail.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1483044517-5770-3-git-send-email-daniel.vetter@ffwll.chhifive-unleashed-5.1
Daniel Vetter
parent
a818286343
commit
05fc03217e
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@ -449,7 +449,7 @@ LRU Scan/Eviction Support
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-------------------------
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.. kernel-doc:: drivers/gpu/drm/drm_mm.c
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:doc: lru scan roaster
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:doc: lru scan roster
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DRM MM Range Allocator Function References
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------------------------------------------
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@ -59,8 +59,8 @@
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*
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* The main data struct is &drm_mm, allocations are tracked in &drm_mm_node.
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* Drivers are free to embed either of them into their own suitable
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* datastructures. drm_mm itself will not do any allocations of its own, so if
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* drivers choose not to embed nodes they need to still allocate them
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* datastructures. drm_mm itself will not do any memory allocations of its own,
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* so if drivers choose not to embed nodes they need to still allocate them
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* themselves.
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*
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* The range allocator also supports reservation of preallocated blocks. This is
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@ -78,7 +78,7 @@
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* steep cliff not a real concern. Removing a node again is O(1).
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*
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* drm_mm supports a few features: Alignment and range restrictions can be
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* supplied. Further more every &drm_mm_node has a color value (which is just an
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* supplied. Furthermore every &drm_mm_node has a color value (which is just an
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* opaque unsigned long) which in conjunction with a driver callback can be used
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* to implement sophisticated placement restrictions. The i915 DRM driver uses
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* this to implement guard pages between incompatible caching domains in the
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@ -296,11 +296,11 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
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* @mm: drm_mm allocator to insert @node into
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* @node: drm_mm_node to insert
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*
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* This functions inserts an already set-up drm_mm_node into the allocator,
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* meaning that start, size and color must be set by the caller. This is useful
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* to initialize the allocator with preallocated objects which must be set-up
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* before the range allocator can be set-up, e.g. when taking over a firmware
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* framebuffer.
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* This functions inserts an already set-up &drm_mm_node into the allocator,
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* meaning that start, size and color must be set by the caller. All other
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* fields must be cleared to 0. This is useful to initialize the allocator with
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* preallocated objects which must be set-up before the range allocator can be
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* set-up, e.g. when taking over a firmware framebuffer.
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*
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* Returns:
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* 0 on success, -ENOSPC if there's no hole where @node is.
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@ -375,7 +375,7 @@ EXPORT_SYMBOL(drm_mm_reserve_node);
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* @sflags: flags to fine-tune the allocation search
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* @aflags: flags to fine-tune the allocation behavior
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*
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* The preallocated node must be cleared to 0.
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* The preallocated @node must be cleared to 0.
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*
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* Returns:
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* 0 on success, -ENOSPC if there's no suitable hole.
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@ -537,7 +537,7 @@ void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new)
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EXPORT_SYMBOL(drm_mm_replace_node);
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/**
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* DOC: lru scan roaster
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* DOC: lru scan roster
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*
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* Very often GPUs need to have continuous allocations for a given object. When
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* evicting objects to make space for a new one it is therefore not most
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@ -549,9 +549,11 @@ EXPORT_SYMBOL(drm_mm_replace_node);
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* The DRM range allocator supports this use-case through the scanning
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* interfaces. First a scan operation needs to be initialized with
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* drm_mm_scan_init() or drm_mm_scan_init_with_range(). The driver adds
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* objects to the roster (probably by walking an LRU list, but this can be
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* freely implemented) (using drm_mm_scan_add_block()) until a suitable hole
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* is found or there are no further evictable objects.
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* objects to the roster, probably by walking an LRU list, but this can be
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* freely implemented. Eviction candiates are added using
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* drm_mm_scan_add_block() until a suitable hole is found or there are no
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* further evictable objects. Eviction roster metadata is tracked in struct
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* &drm_mm_scan.
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*
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* The driver must walk through all objects again in exactly the reverse
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* order to restore the allocator state. Note that while the allocator is used
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@ -559,7 +561,7 @@ EXPORT_SYMBOL(drm_mm_replace_node);
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*
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* Finally the driver evicts all objects selected (drm_mm_scan_remove_block()
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* reported true) in the scan, and any overlapping nodes after color adjustment
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* (drm_mm_scan_evict_color()). Adding and removing an object is O(1), and
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* (drm_mm_scan_color_evict()). Adding and removing an object is O(1), and
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* since freeing a node is also O(1) the overall complexity is
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* O(scanned_objects). So like the free stack which needs to be walked before a
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* scan operation even begins this is linear in the number of objects. It
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@ -705,14 +707,15 @@ EXPORT_SYMBOL(drm_mm_scan_add_block);
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* @scan: the active drm_mm scanner
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* @node: drm_mm_node to remove
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*
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* Nodes _must_ be removed in exactly the reverse order from the scan list as
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* they have been added (e.g. using list_add as they are added and then
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* list_for_each over that eviction list to remove), otherwise the internal
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* Nodes **must** be removed in exactly the reverse order from the scan list as
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* they have been added (e.g. using list_add() as they are added and then
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* list_for_each() over that eviction list to remove), otherwise the internal
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* state of the memory manager will be corrupted.
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*
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* When the scan list is empty, the selected memory nodes can be freed. An
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* immediately following drm_mm_search_free with !DRM_MM_SEARCH_BEST will then
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* return the just freed block (because its at the top of the free_stack list).
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* immediately following drm_mm_insert_node_in_range_generic() or one of the
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* simpler versions of that function with !DRM_MM_SEARCH_BEST will then return
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* the just freed block (because its at the top of the free_stack list).
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*
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* Returns:
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* True if this block should be evicted, false otherwise. Will always
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@ -67,16 +67,29 @@ enum drm_mm_allocator_flags {
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#define DRM_MM_BOTTOMUP DRM_MM_SEARCH_DEFAULT, DRM_MM_CREATE_DEFAULT
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#define DRM_MM_TOPDOWN DRM_MM_SEARCH_BELOW, DRM_MM_CREATE_TOP
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/**
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* struct drm_mm_node - allocated block in the DRM allocator
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*
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* This represents an allocated block in a &drm_mm allocator. Except for
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* pre-reserved nodes inserted using drm_mm_reserve_node() the structure is
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* entirely opaque and should only be accessed through the provided funcions.
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* Since allocation of these nodes is entirely handled by the driver they can be
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* embedded.
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*/
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struct drm_mm_node {
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/** @color: Opaque driver-private tag. */
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unsigned long color;
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/** @start: Start address of the allocated block. */
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u64 start;
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/** @size: Size of the allocated block. */
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u64 size;
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/* private: */
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struct list_head node_list;
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struct list_head hole_stack;
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struct rb_node rb;
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unsigned hole_follows : 1;
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unsigned allocated : 1;
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bool scanned_block : 1;
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unsigned long color;
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u64 start;
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u64 size;
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u64 __subtree_last;
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struct drm_mm *mm;
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#ifdef CONFIG_DRM_DEBUG_MM
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@ -84,7 +97,29 @@ struct drm_mm_node {
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#endif
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};
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/**
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* struct drm_mm - DRM allocator
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*
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* DRM range allocator with a few special functions and features geared towards
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* managing GPU memory. Except for the @color_adjust callback the structure is
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* entirely opaque and should only be accessed through the provided functions
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* and macros. This structure can be embedded into larger driver structures.
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*/
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struct drm_mm {
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/**
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* @color_adjust:
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*
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* Optional driver callback to further apply restrictions on a hole. The
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* node argument points at the node containing the hole from which the
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* block would be allocated (see drm_mm_hole_follows() and friends). The
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* other arguments are the size of the block to be allocated. The driver
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* can adjust the start and end as needed to e.g. insert guard pages.
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*/
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void (*color_adjust)(const struct drm_mm_node *node,
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unsigned long color,
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u64 *start, u64 *end);
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/* private: */
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/* List of all memory nodes that immediately precede a free hole. */
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struct list_head hole_stack;
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/* head_node.node_list is the list of all memory nodes, ordered
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@ -93,14 +128,20 @@ struct drm_mm {
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/* Keep an interval_tree for fast lookup of drm_mm_nodes by address. */
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struct rb_root interval_tree;
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void (*color_adjust)(const struct drm_mm_node *node,
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unsigned long color,
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u64 *start, u64 *end);
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unsigned long scan_active;
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};
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/**
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* struct drm_mm_scan - DRM allocator eviction roaster data
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*
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* This structure tracks data needed for the eviction roaster set up using
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* drm_mm_scan_init(), and used with drm_mm_scan_add_block() and
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* drm_mm_scan_remove_block(). The structure is entirely opaque and should only
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* be accessed through the provided functions and macros. It is meant to be
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* allocated temporarily by the driver on the stack.
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*/
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struct drm_mm_scan {
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/* private: */
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struct drm_mm *mm;
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u64 size;
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@ -159,7 +200,8 @@ static inline bool drm_mm_initialized(const struct drm_mm *mm)
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*
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* Holes are embedded into the drm_mm using the tail of a drm_mm_node.
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* If you wish to know whether a hole follows this particular node,
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* query this function.
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* query this function. See also drm_mm_hole_node_start() and
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* drm_mm_hole_node_end().
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*
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* Returns:
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* True if a hole follows the @node.
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@ -228,23 +270,23 @@ static inline u64 drm_mm_hole_node_end(const struct drm_mm_node *hole_node)
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/**
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* drm_mm_for_each_node - iterator to walk over all allocated nodes
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* @entry: drm_mm_node structure to assign to in each iteration step
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* @mm: drm_mm allocator to walk
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* @entry: &struct drm_mm_node to assign to in each iteration step
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* @mm: &drm_mm allocator to walk
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*
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* This iterator walks over all nodes in the range allocator. It is implemented
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* with list_for_each, so not save against removal of elements.
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* with list_for_each(), so not save against removal of elements.
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*/
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#define drm_mm_for_each_node(entry, mm) \
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list_for_each_entry(entry, drm_mm_nodes(mm), node_list)
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/**
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* drm_mm_for_each_node_safe - iterator to walk over all allocated nodes
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* @entry: drm_mm_node structure to assign to in each iteration step
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* @next: drm_mm_node structure to store the next step
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* @mm: drm_mm allocator to walk
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* @entry: &struct drm_mm_node to assign to in each iteration step
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* @next: &struct drm_mm_node to store the next step
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* @mm: &drm_mm allocator to walk
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*
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* This iterator walks over all nodes in the range allocator. It is implemented
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* with list_for_each_safe, so save against removal of elements.
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* with list_for_each_safe(), so save against removal of elements.
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*/
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#define drm_mm_for_each_node_safe(entry, next, mm) \
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list_for_each_entry_safe(entry, next, drm_mm_nodes(mm), node_list)
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@ -259,13 +301,13 @@ static inline u64 drm_mm_hole_node_end(const struct drm_mm_node *hole_node)
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/**
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* drm_mm_for_each_hole - iterator to walk over all holes
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* @entry: drm_mm_node used internally to track progress
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* @mm: drm_mm allocator to walk
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* @entry: &drm_mm_node used internally to track progress
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* @mm: &drm_mm allocator to walk
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* @hole_start: ulong variable to assign the hole start to on each iteration
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* @hole_end: ulong variable to assign the hole end to on each iteration
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*
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* This iterator walks over all holes in the range allocator. It is implemented
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* with list_for_each, so not save against removal of elements. @entry is used
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* with list_for_each(), so not save against removal of elements. @entry is used
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* internally and will not reflect a real drm_mm_node for the very first hole.
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* Hence users of this iterator may not access it.
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*
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@ -334,6 +376,9 @@ static inline int drm_mm_insert_node_in_range(struct drm_mm *mm,
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* @sflags: flags to fine-tune the allocation search
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* @aflags: flags to fine-tune the allocation behavior
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*
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* This is a simplified version of drm_mm_insert_node_in_range_generic() with no
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* range restrictions applied.
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*
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* The preallocated node must be cleared to 0.
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*
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* Returns:
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@ -434,6 +479,9 @@ void drm_mm_scan_init_with_range(struct drm_mm_scan *scan,
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* @color: opaque tag value to use for the allocation
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* @flags: flags to specify how the allocation will be performed afterwards
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*
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* This is a simplified version of drm_mm_scan_init_with_range() with no range
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* restrictions applied.
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*
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* This simply sets up the scanning routines with the parameters for the desired
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* hole.
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*
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