ALSA: hda - Introduce cache & flush cmd / amp writes

For optimizing the verb executions, a new mechanism to cache the verbs
and amp update commands is introduced.  With the new "write to cache
and flush" way, you can reduce the same verbs that have been written
multiple times.

When codec->cached_write flag is set, the further
snd_hda_codec_write_cache() and snd_hda_codec_amp_stereo() calls will
be performed only on the command or amp cache table, but not sent to
the hardware yet.  Once after you call all commands and update amps,
call snd_hda_codec_resume_amp() and snd_hda_codec_resume_cache().
Then all cached writes and amp updates will be written to the
hardware, and the dirty flags are cleared.

In this implementation, the existing cache table is reused, so
actually no big code change is seen here.  Each cache entry has a new
dirty flag now (so the cache key is now reduced to 31bit).

As a good side-effect by this change, snd_hda_codec_resume_*() will no
longer execute verbs that have been already issued during the resume
phase by checking the dirty flags.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 4 insertions, 8 deletions

diff --git a/sound/pci/hda/hda_codec.h b/sound/pci/hda/hda_codec.h
index 8665540e55aa..cab39b23d37c 100644
--- a/sound/pci/hda/hda_codec.h
+++ b/sound/pci/hda/hda_codec.h
@@ -719,9 +719,10 @@ struct hda_codec_ops {
 
 /* record for amp information cache */
 struct hda_cache_head {
-        u32 key;                /* hash key */
+        u32 key:31;             /* hash key */
+        u32 dirty:1;
         u16 val;                /* assigned value */
-        u16 next;               /* next link; -1 = terminal */
+        u16 next;
 };
 
 struct hda_amp_info {
@@ -867,6 +868,7 @@ struct hda_codec {
         unsigned int no_jack_detect:1;  /* Machine has no jack-detection */
         unsigned int pcm_format_first:1; /* PCM format must be set first */
         unsigned int epss:1;            /* supporting EPSS? */
+        unsigned int cached_write:1;    /* write only to caches */
 #ifdef CONFIG_PM
         unsigned int power_on :1;       /* current (global) power-state */
         unsigned int d3_stop_clk:1;     /* support D3 operation without BCLK */
@@ -952,7 +954,6 @@ void snd_hda_sequence_write(struct hda_codec *codec,
 int snd_hda_queue_unsol_event(struct hda_bus *bus, u32 res, u32 res_ex);
 
 /* cached write */
-#ifdef CONFIG_PM
 int snd_hda_codec_write_cache(struct hda_codec *codec, hda_nid_t nid,
                               int direct, unsigned int verb, unsigned int parm);
 void snd_hda_sequence_write_cache(struct hda_codec *codec,
@@ -960,11 +961,6 @@ void snd_hda_sequence_write_cache(struct hda_codec *codec,
 int snd_hda_codec_update_cache(struct hda_codec *codec, hda_nid_t nid,
                               int direct, unsigned int verb, unsigned int parm);
 void snd_hda_codec_resume_cache(struct hda_codec *codec);
-#else
-#define snd_hda_codec_write_cache       snd_hda_codec_write
-#define snd_hda_codec_update_cache      snd_hda_codec_write
-#define snd_hda_sequence_write_cache    snd_hda_sequence_write
-#endif
 
 /* the struct for codec->pin_configs */
 struct hda_pincfg {