ALSA: intelhdmi - sticky stream id and format

We tracked down the first-0.5s-hdmi-audio-samples-lost problem to the
AC_VERB_SET_CHANNEL_STREAMID command. It is suspected that many HDMI
sinks need some time to adapt to the new state.

The workaround is to avoid changing stream id/format whenever possible.
Proposed by David.

Signed-off-by: David Härdeman <david@hardeman.nu>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/pci/hda/patch_intelhdmi.c b/sound/pci/hda/patch_intelhdmi.c
index abb056fde67a53f93532d597d18540961b1952b6..8a1cf9d7e5cebcd68089fbde07ce35e07a33d903 100644 (file)
--- a/sound/pci/hda/patch_intelhdmi.c
+++ b/sound/pci/hda/patch_intelhdmi.c
@@ -772,6 +772,31 @@ static void intel_hdmi_unsol_event(struct hda_codec *codec, unsigned int res)
  * Callbacks
  */
 
+static void hdmi_setup_stream(struct hda_codec *codec, hda_nid_t nid,
+                             u32 stream_tag, int format)
+{
+       int tag;
+       int fmt;
+
+       tag = snd_hda_codec_read(codec, nid, 0, AC_VERB_GET_CONV, 0) >> 4;
+       fmt = snd_hda_codec_read(codec, nid, 0, AC_VERB_GET_STREAM_FORMAT, 0);
+
+       snd_printdd("hdmi_setup_stream: "
+                   "NID=0x%x, %sstream=0x%x, %sformat=0x%x\n",
+                   nid,
+                   tag == stream_tag ? "" : "new-",
+                   stream_tag,
+                   fmt == format ? "" : "new-",
+                   format);
+
+       if (tag != stream_tag)
+               snd_hda_codec_write(codec, nid, 0,
+                                   AC_VERB_SET_CHANNEL_STREAMID, stream_tag << 4);
+       if (fmt != format)
+               snd_hda_codec_write(codec, nid, 0,
+                                   AC_VERB_SET_STREAM_FORMAT, format);
+}
+
 static int intel_hdmi_playback_pcm_prepare(struct hda_pcm_stream *hinfo,
                                           struct hda_codec *codec,
                                           unsigned int stream_tag,
@@ -783,7 +808,7 @@ static int intel_hdmi_playback_pcm_prepare(struct hda_pcm_stream *hinfo,
 
        hdmi_setup_audio_infoframe(codec, hinfo->nid, substream);
 
-       snd_hda_codec_setup_stream(codec, hinfo->nid, stream_tag, 0, format);
+       hdmi_setup_stream(codec, hinfo->nid, stream_tag, format);
        return 0;
 }
 
@@ -791,7 +816,6 @@ static int intel_hdmi_playback_pcm_cleanup(struct hda_pcm_stream *hinfo,
                                           struct hda_codec *codec,
                                           struct snd_pcm_substream *substream)
 {
-       snd_hda_codec_cleanup_stream(codec, hinfo->nid);
        return 0;
 }