[alsa-devel] [PATCH RFC 2/2] Add workaround for conflicting IEC958 controls for HD-audio

[Takashi Iwai]

When both an SPDIF and an HDMI output are present on HD-audio, both
try to access IEC958 controls with index=0 although one of them must
be wrong.  For avoiding this conflict, the recent kernel code moves
the IEC958 controls of an SPDIF with device=1 once when the conflict
happens.

In this patch, the corresponding support is added in alsa-lib side.
The new "skip_rest" boolean flag is added to the hooked element
definition which indicates that the rest of element array will be
ignored once when this element is present and evaluated.  With this
new flag, the HD-audio config takes device=1 primarily, then take
device=0 as fallback.

Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 src/conf/cards/HDA-Intel.conf | 16 ++++++++++++++++
 src/control/setup.c           | 19 ++++++++++++++++---
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/src/conf/cards/HDA-Intel.conf b/src/conf/cards/HDA-Intel.conf
index d4f2667..55fb624 100644
--- a/src/conf/cards/HDA-Intel.conf
+++ b/src/conf/cards/HDA-Intel.conf
@@ -113,6 +113,22 @@ HDA-Intel.pcm.iec958.0 {
 			hook_args [
 			{
 				name "IEC958 Playback Default"
+				device 1
+				optional true
+				lock true
+				preserve true
+				value [ $AES0 $AES1 $AES2 $AES3 ]
+			}
+			{
+				name "IEC958 Playback Switch"
+				device 1
+				optional true
+				value true
+				# if this element is present, skip the rest
+				skip_rest true
+			}
+			{
+				name "IEC958 Playback Default"
 				lock true
 				preserve true
 				value [ $AES0 $AES1 $AES2 $AES3 ]
diff --git a/src/control/setup.c b/src/control/setup.c
index bd3599d..f23bf2c 100644
--- a/src/control/setup.c
+++ b/src/control/setup.c
@@ -396,7 +396,7 @@ static int snd_config_get_ctl_elem_value(snd_config_t *conf,
 	return 0;
 }
 
-static int add_elem(snd_sctl_t *h, snd_config_t *_conf, snd_config_t *private_data)
+static int add_elem(snd_sctl_t *h, snd_config_t *_conf, snd_config_t *private_data, int *quit)
 {
 	snd_config_t *conf;
 	snd_config_iterator_t i, next;
@@ -408,6 +408,7 @@ static int add_elem(snd_sctl_t *h, snd_config_t *_conf, snd_config_t *private_da
 	int lock = 0;
 	int preserve = 0;
 	int optional = 0;
+	int skip_rest = 0;
 	snd_config_t *value = NULL, *mask = NULL;
 	snd_sctl_elem_t *elem = NULL;
 	int err;
@@ -491,6 +492,13 @@ static int add_elem(snd_sctl_t *h, snd_config_t *_conf, snd_config_t *private_da
 			optional = err;
 			continue;
 		}
+		if (strcmp(id, "skip_rest") == 0) {
+			err = snd_config_get_bool(n);
+			if (err < 0)
+				goto _err;
+			skip_rest = err;
+			continue;
+		}
 		SNDERR("Unknown field %s", id);
 		return -EINVAL;
 	}
@@ -539,6 +547,9 @@ static int add_elem(snd_sctl_t *h, snd_config_t *_conf, snd_config_t *private_da
 		if (! optional)
 			SNDERR("Cannot obtain info for CTL elem (%s,'%s',%li,%li,%li): %s", snd_ctl_elem_iface_name(iface), name, index, device, subdevice, snd_strerror(err));
 		goto _err;
+	} else {
+		if (skip_rest)
+			*quit = 1;
 	}
 	snd_ctl_elem_value_set_id(elem->val, elem->id);
 	snd_ctl_elem_value_set_id(elem->old, elem->id);
@@ -594,7 +605,7 @@ int snd_sctl_build(snd_sctl_t **sctl, snd_ctl_t *handle, snd_config_t *conf, snd
 {
 	snd_sctl_t *h;
 	snd_config_iterator_t i, next;
-	int err;
+	int err, quit = 0;
 
 	assert(sctl);
 	assert(handle);
@@ -614,11 +625,13 @@ int snd_sctl_build(snd_sctl_t **sctl, snd_ctl_t *handle, snd_config_t *conf, snd
 	INIT_LIST_HEAD(&h->elems);
 	snd_config_for_each(i, next, conf) {
 		snd_config_t *n = snd_config_iterator_entry(i);
-		err = add_elem(h, n, private_data);
+		err = add_elem(h, n, private_data, &quit);
 		if (err < 0) {
 			free_elems(h);
 			return err;
 		}
+		if (quit)
+			break;
 	}
 	*sctl = h;
 	return 0;
-- 
1.7.12.2