ASoC: soc-cache: Cache a pointer to the last accessed rbnode

Whenever we are doing a read or a write through the rbtree code, we'll
cache a pointer to the rbnode.  To avoid looking up the register
everytime we do a read or a write, we first check if it can be found in
the cached register block, otherwise we traverse the rbtree and finally
cache the rbnode for future use.

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

diff --git a/sound/soc/soc-cache.c b/sound/soc/soc-cache.c
index 78c9869615dfa02c5273ace6d9a1a948bbe8a77f..5cd23daff4adbe0b81ab83976388d67e4ca73af5 100644 (file)
--- a/sound/soc/soc-cache.c
+++ b/sound/soc/soc-cache.c
@@ -604,6 +604,7 @@ struct snd_soc_rbtree_node {
 
 struct snd_soc_rbtree_ctx {
        struct rb_root root;
+       struct snd_soc_rbtree_node *cached_rbnode;
 };
 
 static inline void snd_soc_rbtree_get_base_top_reg(
@@ -780,11 +781,28 @@ static int snd_soc_rbtree_cache_write(struct snd_soc_codec *codec,
        struct rb_node *node;
        unsigned int val;
        unsigned int reg_tmp;
+       unsigned int base_reg, top_reg;
        unsigned int pos;
        int i;
        int ret;
 
        rbtree_ctx = codec->reg_cache;
+       /* look up the required register in the cached rbnode */
+       rbnode = rbtree_ctx->cached_rbnode;
+       if (rbnode) {
+               snd_soc_rbtree_get_base_top_reg(rbnode, &base_reg, &top_reg);
+               if (reg >= base_reg && reg <= top_reg) {
+                       reg_tmp = reg - base_reg;
+                       val = snd_soc_rbtree_get_register(rbnode, reg_tmp);
+                       if (val == value)
+                               return 0;
+                       snd_soc_rbtree_set_register(rbnode, reg_tmp, value);
+                       return 0;
+               }
+       }
+       /* if we can't locate it in the cached rbnode we'll have
+        * to traverse the rbtree looking for it.
+        */
        rbnode = snd_soc_rbtree_lookup(&rbtree_ctx->root, reg);
        if (rbnode) {
                reg_tmp = reg - rbnode->base_reg;
@@ -792,6 +810,7 @@ static int snd_soc_rbtree_cache_write(struct snd_soc_codec *codec,
                if (val == value)
                        return 0;
                snd_soc_rbtree_set_register(rbnode, reg_tmp, value);
+               rbtree_ctx->cached_rbnode = rbnode;
        } else {
                /* bail out early, no need to create the rbnode yet */
                if (!value)
@@ -813,6 +832,7 @@ static int snd_soc_rbtree_cache_write(struct snd_soc_codec *codec,
                                                                     reg, value);
                                if (ret)
                                        return ret;
+                               rbtree_ctx->cached_rbnode = rbnode_tmp;
                                return 0;
                        }
                }
@@ -835,6 +855,7 @@ static int snd_soc_rbtree_cache_write(struct snd_soc_codec *codec,
                }
                snd_soc_rbtree_set_register(rbnode, 0, value);
                snd_soc_rbtree_insert(&rbtree_ctx->root, rbnode);
+               rbtree_ctx->cached_rbnode = rbnode;
        }
 
        return 0;
@@ -845,13 +866,28 @@ static int snd_soc_rbtree_cache_read(struct snd_soc_codec *codec,
 {
        struct snd_soc_rbtree_ctx *rbtree_ctx;
        struct snd_soc_rbtree_node *rbnode;
+       unsigned int base_reg, top_reg;
        unsigned int reg_tmp;
 
        rbtree_ctx = codec->reg_cache;
+       /* look up the required register in the cached rbnode */
+       rbnode = rbtree_ctx->cached_rbnode;
+       if (rbnode) {
+               snd_soc_rbtree_get_base_top_reg(rbnode, &base_reg, &top_reg);
+               if (reg >= base_reg && reg <= top_reg) {
+                       reg_tmp = reg - base_reg;
+                       *value = snd_soc_rbtree_get_register(rbnode, reg_tmp);
+                       return 0;
+               }
+       }
+       /* if we can't locate it in the cached rbnode we'll have
+        * to traverse the rbtree looking for it.
+        */
        rbnode = snd_soc_rbtree_lookup(&rbtree_ctx->root, reg);
        if (rbnode) {
                reg_tmp = reg - rbnode->base_reg;
                *value = snd_soc_rbtree_get_register(rbnode, reg_tmp);
+               rbtree_ctx->cached_rbnode = rbnode;
        } else {
                /* uninitialized registers default to 0 */
                *value = 0;
@@ -902,6 +938,7 @@ static int snd_soc_rbtree_cache_init(struct snd_soc_codec *codec)
 
        rbtree_ctx = codec->reg_cache;
        rbtree_ctx->root = RB_ROOT;
+       rbtree_ctx->cached_rbnode = NULL;
 
        if (!codec->reg_def_copy)
                return 0;