tools include UAPI: Sync the sound/asound.h copy with the kernel sources

Picking the changes from:

  102882b5c62f6bfe ("ALSA: document that struct __snd_pcm_mmap_control64 is messed up")
  9f656705c5faa18a ("ALSA: pcm: rewrite snd_pcm_playback_silence()")

Silencing these perf build warnings:

  Warning: Kernel ABI header at 'tools/include/uapi/sound/asound.h' differs from latest version at 'include/uapi/sound/asound.h'
  diff -u tools/include/uapi/sound/asound.h include/uapi/sound/asound.h

Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: loongson-kernel@lists.loongnix.cn
Link: https://lore.kernel.org/r/5606e7989bbb029c400117f2e455ab995208266f.1683712945.git.siyanteng@loongson.cn
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/include/uapi/sound/asound.h b/tools/include/uapi/sound/asound.h
index de6810e94abed3e91de3ef42d1eaca0353c1b8d3..0aa955aa82463a63872a037dbd6ef7d3f08dfec1 100644 (file)
--- a/tools/include/uapi/sound/asound.h
+++ b/tools/include/uapi/sound/asound.h
@@ -429,9 +429,14 @@ struct snd_pcm_sw_params {
        snd_pcm_uframes_t avail_min;            /* min avail frames for wakeup */
        snd_pcm_uframes_t xfer_align;           /* obsolete: xfer size need to be a multiple */
        snd_pcm_uframes_t start_threshold;      /* min hw_avail frames for automatic start */
-       snd_pcm_uframes_t stop_threshold;       /* min avail frames for automatic stop */
-       snd_pcm_uframes_t silence_threshold;    /* min distance from noise for silence filling */
-       snd_pcm_uframes_t silence_size;         /* silence block size */
+       /*
+        * The following two thresholds alleviate playback buffer underruns; when
+        * hw_avail drops below the threshold, the respective action is triggered:
+        */
+       snd_pcm_uframes_t stop_threshold;       /* - stop playback */
+       snd_pcm_uframes_t silence_threshold;    /* - pre-fill buffer with silence */
+       snd_pcm_uframes_t silence_size;         /* max size of silence pre-fill; when >= boundary,
+                                                * fill played area with silence immediately */
        snd_pcm_uframes_t boundary;             /* pointers wrap point */
        unsigned int proto;                     /* protocol version */
        unsigned int tstamp_type;               /* timestamp type (req. proto >= 2.0.12) */
@@ -570,7 +575,8 @@ struct __snd_pcm_mmap_status64 {
 struct __snd_pcm_mmap_control64 {
        __pad_before_uframe __pad1;
        snd_pcm_uframes_t appl_ptr;      /* RW: appl ptr (0...boundary-1) */
-       __pad_before_uframe __pad2;
+       __pad_before_uframe __pad2;      // This should be __pad_after_uframe, but binary
+                                        // backwards compatibility constraints prevent a fix.
 
        __pad_before_uframe __pad3;
        snd_pcm_uframes_t  avail_min;    /* RW: min available frames for wakeup */