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drm/mm: Some doc polish

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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.ch
This commit is contained in:
Daniel Vetter
2016-12-29 21:48:23 +01:00
parent a818286343
commit 05fc03217e
3 changed files with 89 additions and 38 deletions
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41
drivers/gpu/drm/drm_mm.c
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@@ -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