[alsa-devel] [PATCH v3] stop setup_dig_out_stream() causing clicks

[Laurence Darby]

Starting audio or seeking in various music players causes
setup_dig_out_stream() to be called, which resets the SPDIF stream,
which caused one DAC (but not another) to make a clicking noise every
time.

This patch ensures the reset only happens when it needs to, which is
when the format changes, and makes the code a little more readable.

Signed-off-by: Laurence Darby <ldarby at tuffmail.com>
---

Takashi Iwai wrote:

> > +	reset = codec->spdif_status_reset &&
> > +		spdif->ctls & AC_DIG1_ENABLE &&
> > +		curr_fmt != format;
> 
> Better to put parentheses around the bit operations when combined with
> logical operations.  gcc would suggest it, too, I thought.
> 

gcc doesn't warn about it, but it does on code like this:

	reset = codec->spdif_status_reset &&
		spdif->ctls & AC_DIG1_ENABLE + 0 &&
		curr_fmt != format;

which suggests putting them around the +. But since you spotted it, I've put them back in.

Regards,
Laurence


 sound/pci/hda/hda_codec.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index 38fdefc..2b21906 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -4718,10 +4718,20 @@ EXPORT_SYMBOL_HDA(snd_hda_input_mux_put);
 static void setup_dig_out_stream(struct hda_codec *codec, hda_nid_t nid,
 				 unsigned int stream_tag, unsigned int format)
 {
-	struct hda_spdif_out *spdif = snd_hda_spdif_out_of_nid(codec, nid);
-
-	/* turn off SPDIF once; otherwise the IEC958 bits won't be updated */
-	if (codec->spdif_status_reset && (spdif->ctls & AC_DIG1_ENABLE))
+	struct hda_spdif_out *spdif;
+	unsigned int curr_fmt;
+	bool reset;
+
+	spdif = snd_hda_spdif_out_of_nid(codec, nid);
+	curr_fmt = snd_hda_codec_read(codec, nid, 0,
+				      AC_VERB_GET_STREAM_FORMAT, 0);
+	reset = codec->spdif_status_reset &&
+		(spdif->ctls & AC_DIG1_ENABLE) &&
+		curr_fmt != format;
+	
+	/* turn off SPDIF if needed; otherwise the IEC958 bits won't be
+	   updated */
+	if (reset)
 		set_dig_out_convert(codec, nid,
 				    spdif->ctls & ~AC_DIG1_ENABLE & 0xff,
 				    -1);
@@ -4733,7 +4743,7 @@ static void setup_dig_out_stream(struct hda_codec *codec, hda_nid_t nid,
 						   format);
 	}
 	/* turn on again (if needed) */
-	if (codec->spdif_status_reset && (spdif->ctls & AC_DIG1_ENABLE))
+	if (reset)
 		set_dig_out_convert(codec, nid,
 				    spdif->ctls & 0xff, -1);
 }
-- 
1.7.12.1