Re: [PATCH] ALSA: hda - hdmi: Fix channel map switch not taking effect

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Takashi Iwai kirjoitti 2013-10-07 10:48:
At Wed,  2 Oct 2013 21:13:32 +0300,
Anssi Hannula wrote:

Currently hdmi_setup_audio_infoframe() reprograms the HDA channel
mapping only when the infoframe is not up-to-date or the non-PCM flag
has changed.

However, when just the channel map has been changed, the infoframe may
still be up-to-date and non-PCM flag may not have changed, so the new
channel map is not actually programmed into the HDA codec.

Notably, this failing case is also always triggered when the device is
already in a prepared state and a new channel map is configured while
changing only the channel positions (for example, plain
"speaker-test -c2 -m FR,FL").

Fix that by keeping track of the last programmed channel map and making
hdmi_setup_audio_infoframe() always update the hardware mapping if the
channel map has changed.

Hmm, maybe it's easier (and safer) to remove the check and always call
hdmi_setup_channel_mapping()?  Of course, the drawback is the
unnecessary verbs, but it's not too much.

Easier, yes. I don't really have that good of an idea how big of a delay
do 8 write verbs cause, so I'll rely on your judgment :)

I guess I could replace the writes with read-and-write-if-differs cycles
when I add the set_slot ops for ATI/AMD, since it seems to be used for
other similar cases (like channel count)?

Signed-off-by: Anssi Hannula <anssi.hannula@xxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
---

BTW, is there some mechanism preventing hdmi_chmap_ctl_put() to be called
at the same time with generic_hdmi_playback_pcm_prepare() that I didn't
see with a quick look?
Both of them call hdmi_setup_audio_infoframe() which is not thread-safe.

Yeah, we need to introduce a mutex there.

I guess hdmi_present_sense() is the same, as it can also call
hdmi_setup_audio_infoframe()?

BTW, shouldn't hdmi_present_sense() call hdmi_setup_audio_infoframe() always
when eld_changed is true? hdmi_setup_audio_infoframe() does not do its
stuff if !monitor_present, so if one starts playback before plugging in,
the channel mappings etc will never be set even when plug-in happens
(from what I can see, that is -  did not test yet).


thanks,

Takashi

sound/pci/hda/patch_hdmi.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
index 7ea0245..09f38a1 100644
--- a/sound/pci/hda/patch_hdmi.c
+++ b/sound/pci/hda/patch_hdmi.c
@@ -74,6 +74,8 @@ struct hdmi_spec_per_pin {
	bool non_pcm;
	bool chmap_set;		/* channel-map override by ALSA API? */
	unsigned char chmap[8]; /* ALSA API channel-map */
+	bool last_chmap_set;	/* channel-map override programmed? */
+	unsigned char last_chmap[8]; /* last programmed channel-map */
	char pcm_name[8];	/* filled in build_pcm callbacks */
};

@@ -955,15 +957,21 @@ static void hdmi_setup_audio_infoframe(struct hda_codec *codec,
					    ai.bytes, sizeof(ai));
		hdmi_start_infoframe_trans(codec, pin_nid);
	} else {
-		/* For non-pcm audio switch, setup new channel mapping
-		 * accordingly */
-		if (per_pin->non_pcm != non_pcm)
+		/* For non-pcm audio switch or channel-map switch,
+		 * setup new channel mapping accordingly */
+		if (per_pin->non_pcm != non_pcm
+		    || per_pin->chmap_set != per_pin->last_chmap_set
+ || (per_pin->chmap_set && memcmp(per_pin->chmap, per_pin->last_chmap,
+						     ARRAY_SIZE(per_pin->chmap)) != 0))
			hdmi_setup_channel_mapping(codec, pin_nid, non_pcm, ca,
						   channels, per_pin->chmap,
						   per_pin->chmap_set);
	}

	per_pin->non_pcm = non_pcm;
+	per_pin->last_chmap_set = per_pin->chmap_set;
+	if (per_pin->chmap_set)
+ memcpy(per_pin->last_chmap, per_pin->chmap, ARRAY_SIZE(per_pin->chmap));
}


--
1.8.1.5

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