On Thu, 2010-11-04 at 14:49 -0400, Mark Brown wrote:
On Thu, Nov 04, 2010 at 02:22:44PM +0000, Dimitris Papastamos wrote:
This patch adds support for rbtree compression when storing the register cache. It does this by not adding any uninitialized registers (those whose value is 0). If any of those registers is written with a nonzero value they get added into the rbtree.
- rbtree_ctx = codec->reg_cache;
- for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
rbnode = rb_entry(node, struct snd_soc_rbtree_node, node);if (!rbnode->dirty)continue;snd_soc_cache_read(codec, rbnode->reg, &val);snd_soc_write(codec, rbnode->reg, val);dev_dbg(codec->dev, "Synced register %#x, value = %#x\n",rbnode->reg, val);Hrm, dirty handling is kind of interesting. It is unconditionally set in the write function and never cleared so we'll always rewrite a register if it's ever been touched. Is it worth remembering the default values and just comparing with them, the memory overhead will probably be low since we only have one bitfield value here... (and remember that we'll be unlikely to allocate memory in 21 byte packed hunks with no overhead...).
Yes, I have deliberately not cleared those bits because at the moment I don't the default value of the register saved anywhere. So what I will do is, I will save the default value, and then I will only sync those registers whose value differs from their default value.
Thanks, Dimitrios