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drm: Fix kerneldoc for drm_mm_scan_remove_block() 

The nodes must be removed in the *reverse* order. This is correct in the
overview, but backwards in the function description. Whilst here add
Intel's copyright statement and tweak some formatting.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161222083641.2691-23-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2016-12-22 08:36:25 +00:00 committed by Daniel Vetter
parent 7173320758
commit ba004e39b1
2 changed files with 31 additions and 22 deletions
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34
drivers/gpu/drm/drm_mm.c
View File

@ -1,6 +1,7 @@
/**************************************************************************
*
* Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND., USA.
* Copyright 2016 Intel Corporation
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
@ -31,9 +32,9 @@
* 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.
* 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.
*
@ -67,7 +68,7 @@
* 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.
* dependencies 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
@ -78,14 +79,14 @@
*
* 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
* 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
* 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.
* 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.
@ -510,7 +511,7 @@ EXPORT_SYMBOL(drm_mm_insert_node_in_range_generic);
*
* 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.
* allocator. It is a bug to call this function on a unallocated node.
*/
void drm_mm_remove_node(struct drm_mm_node *node)
{
@ -689,16 +690,16 @@ EXPORT_SYMBOL(drm_mm_replace_node);
* 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.
* lots of (smaller) objects unnecessarily.
*
* 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
* drm_mm_init_scan() or drm_mm_init_scan_with_range(). 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.
* evictable object.
*
* The the driver must walk through all objects again in exactly the reverse
* 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.
*
@ -838,9 +839,10 @@ EXPORT_SYMBOL(drm_mm_scan_add_block);
* 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.
* 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

19
include/drm/drm_mm.h
View File

@ -1,6 +1,7 @@
/**************************************************************************
*
* Copyright 2006-2008 Tungsten Graphics, Inc., Cedar Park, TX. USA.
* Copyright 2016 Intel Corporation
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
@ -117,7 +118,10 @@ struct drm_mm {
* drm_mm_node_allocated - checks whether a node is allocated
* @node: drm_mm_node to check
*
* Drivers should use this helpers for proper encapusulation of drm_mm
* Drivers are required to clear a node prior to using it with the
* drm_mm range manager.
*
* Drivers should use this helper for proper encapsulation of drm_mm
* internals.
*
* Returns:
@ -132,7 +136,10 @@ static inline bool drm_mm_node_allocated(const struct drm_mm_node *node)
* drm_mm_initialized - checks whether an allocator is initialized
* @mm: drm_mm to check
*
* Drivers should use this helpers for proper encapusulation of drm_mm
* Drivers should clear the struct drm_mm prior to initialisation if they
* want to use this function.
*
* Drivers should use this helper for proper encapsulation of drm_mm
* internals.
*
* Returns:
@ -152,8 +159,8 @@ static inline u64 __drm_mm_hole_node_start(const struct drm_mm_node *hole_node)
* drm_mm_hole_node_start - computes the start of the hole following @node
* @hole_node: drm_mm_node which implicitly tracks the following hole
*
* This is useful for driver-sepific debug dumpers. Otherwise drivers should not
* inspect holes themselves. Drivers must check first whether a hole indeed
* This is useful for driver-specific debug dumpers. Otherwise drivers should
* not inspect holes themselves. Drivers must check first whether a hole indeed
* follows by looking at node->hole_follows.
*
* Returns:
@ -174,8 +181,8 @@ static inline u64 __drm_mm_hole_node_end(const struct drm_mm_node *hole_node)
* drm_mm_hole_node_end - computes the end of the hole following @node
* @hole_node: drm_mm_node which implicitly tracks the following hole
*
* This is useful for driver-sepific debug dumpers. Otherwise drivers should not
* inspect holes themselves. Drivers must check first whether a hole indeed
* This is useful for driver-specific debug dumpers. Otherwise drivers should
* not inspect holes themselves. Drivers must check first whether a hole indeed
* follows by looking at node->hole_follows.
*
* Returns: