On Thu, May 07, 2015 at 11:33:59AM +0100, Charles Keepax wrote:
Some CODECs have a significant number of DAPM routes and for each route, when it is added to the card, the entire card widget list must be
The idea here is good but I'm having a hard time loving the implementation. It feels like it's hacking this specific implementation in many different places without really abstracting things - having a neat trick hidden in one place would be one thinng but it's spread through several different places.
+static struct snd_soc_dapm_widget * +dapm_check_path_cache(const char *name, struct snd_soc_dapm_widget *w, int n) +{
- int i;
- if (w) {
for (i = 0; i < n; i++) {if (!strcmp(name, w->name))return w;w = list_next_entry(w, list);}
This will not be happy if there are fewer than n entries to look at.
static int snd_soc_dapm_add_route(struct snd_soc_dapm_context *dapm,
const struct snd_soc_dapm_route *route)
const struct snd_soc_dapm_route *route,struct snd_soc_dapm_path *cache)
The fact that we're directly using the path structure as the type for the cache here is a warning flag, it means that everywhere that knows there is a cache at all needs to know about the specific type of the cache. If we were to improve the cache in the future, for example doing something like building a hash that maps names to widgets for the duration of probe, then everywhere would need to change.
- if (cache) {
wsink = dapm_check_path_cache(sink, cache->sink, 2);wsource = dapm_check_path_cache(source, cache->source, 2);if (wsink && wsource)goto skip_search;- }
This is the only place where we have _check_path_cache() calls so n is always 2 here and it is unclear where that number comes from or what it means without going and peering at the implementation and the commit log. It seems it would be better to hide that number inside the function.
+skip_search:
- if (cache) {
cache->sink = wsink;cache->source = wsource;- }
Putting this into a store hit function would be good.
mutex_lock_nested(&dapm->card->dapm_mutex, SND_SOC_DAPM_CLASS_INIT); for (i = 0; i < num; i++) {
r = snd_soc_dapm_add_route(dapm, route);
r = snd_soc_dapm_add_route(dapm, route, &cache);
Should we just have the cache in the dapm context or the card instead of locally? It's only two pointers at the minute so there doesn't seem to be much cost from keeping it around and it might generate somme more hits for some use cases. Or to put it another way why is the cache optional and created and re-created here like this?