Commit 6399aea6 authored Oct 21, 2015 by Nikesh Oswal Committed by Mark Brown Nov 16, 2015

regmap: rbtree: When adding a reg do a bsearch for target node



A binary search is much more efficient rather than iterating
over the rbtree in ascending order which the current code is
doing.

During initialisation the reg defaults are written to the
cache in a large chunk and these are always sorted in the
ascending order so for this situation ideally we should have
iterated the rbtree in descending order.

But at runtime the drivers may write into the cache in any
random order so this patch selects to use a bsearch to give
an optimal runtime performance and also at initialisation
time when reg defaults are written the performance of binary
search would be much better than iterating in ascending order
which the current code was doing.

Signed-off-by: Nikesh Oswal <Nikesh.Oswal@wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

parent 8005c49d

drivers/base/regmap/regcache-rbtree.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -413,8 +413,8 @@ static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
		max = reg + max_dist;

		/* look for an adjacent register to the one we are about to add */
		for (node = rb_first(&rbtree_ctx->root); node;
		node = rb_next(node)) {
		node = rbtree_ctx->root.rb_node;
		while (node) {
		rbnode_tmp = rb_entry(node, struct regcache_rbtree_node,
		node);

		@@ -425,6 +425,11 @@ static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
		new_base_reg = min(reg, base_reg);
		new_top_reg = max(reg, top_reg);
		} else {
		if (max < base_reg)
		node = node->rb_left;
		else
		node = node->rb_right;

		continue;
		}