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SubjectRe: [PATCH 3/8] regmap: Add the rbtree cache support
On Fri, Sep 02, 2011 at 10:22:58PM +0200, Lars-Peter Clausen wrote:
> 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.

Yes.

Thanks,
Dimitris


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