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    SubjectRe: [PATCH 3/8] regmap: Add the rbtree cache support
    On 09/02/2011 05:46 PM, Dimitris Papastamos wrote:
    > This patch adds support for the rbtree cache compression type.
    >
    > Each rbnode manages a variable length block of registers. There can be no
    > two nodes with overlapping blocks. Each block has a base register and a
    > currently top register, all the other registers, if any, lie in between these
    > two and in ascending order.
    >
    > The reasoning behind the construction of this rbtree is simple. In the
    > snd_soc_rbtree_cache_init() function, we iterate over the register defaults
    > provided by the regcache core. For each register value that is non-zero we
    > insert it in the rbtree. In order to determine in which rbnode we need
    > to add the register, we first look if there is another register already
    > added that is adjacent to the one we are about to add. If that is the case
    > we append it in that rbnode block, otherwise we create a new rbnode
    > with a single register in its block and add it to the tree.
    >
    > There are various optimizations across the implementation to speed up lookups
    > by caching the most recently used rbnode.
    >
    > Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
    > [...]
    > +
    > +static int regcache_rbtree_init(struct regmap *map)
    > +{
    > + struct regcache_rbtree_ctx *rbtree_ctx;
    > + int i;
    > + int ret;
    > +
    > + map->cache = kmalloc(sizeof *rbtree_ctx, GFP_KERNEL);
    > + if (!map->cache)
    > + return -ENOMEM;
    > +
    > + rbtree_ctx = map->cache;
    > + rbtree_ctx->root = RB_ROOT;
    > + rbtree_ctx->cached_rbnode = NULL;
    > +
    > + if (!map->cache_defaults)
    > + return 0;
    > +
    > + for (i = 0; i < map->num_cache_defaults_raw; ++i) {
    > + ret = regcache_lookup_reg(map, i);
    > + if (ret < 0)
    > + continue;
    > + ret = regcache_rbtree_write(map,
    > + map->cache_defaults[ret].reg,
    > + map->cache_defaults[ret].def);
    > + if (ret)
    > + goto err;
    > + }

    You can iterate over the caches_defaults elements directly.

    [...]
    > diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
    > index dfefe40..2b148d4 100644
    > --- a/drivers/base/regmap/regcache.c
    > +++ b/drivers/base/regmap/regcache.c
    > @@ -19,6 +19,9 @@ static const struct regcache_ops *cache_types[] = {
    > #ifdef CONFIG_REGCACHE_INDEXED
    > &regcache_indexed_ops,
    > #endif
    > +#ifdef CONFIG_REGCACHE_RBTREE

    This symbol is also not defined. It looks as if all the Kconfig changes are not
    included in the patchset.

    > + &regcache_rbtree_ops,
    > +#endif
    > };




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