From: David Henningsson <david.henningsson@canonical.com>
Date: Wed, 5 Jun 2013 14:52:10 +0000 (+0200)
Subject: chmap: Always succeed setting the map to what it already is
X-Git-Tag: v1.0.27.2~3
X-Git-Url: https://git.alsa-project.org/?a=commitdiff_plain;h=d20e24e5d1614354e9c8195ed0b11fe089c489e4;p=alsa-lib.git

chmap: Always succeed setting the map to what it already is

If we try to set the channel map to what it already is, this should
always succeed. E g, speaker-test can do this sometimes.

Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---

diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
index 7ec1f0e5..ca4d416f 100644
--- a/src/pcm/pcm.c
+++ b/src/pcm/pcm.c
@@ -7361,6 +7361,13 @@ OBSOLETE1(snd_pcm_sw_params_get_silence_size, ALSA_0.9, ALSA_0.9.0rc4);
 
 #endif /* DOC_HIDDEN */
 
+static int chmap_equal(const snd_pcm_chmap_t *a, const snd_pcm_chmap_t *b)
+{
+	if (a->channels != b->channels)
+		return 0;
+	return !memcmp(a->pos, b->pos, a->channels * sizeof(a->pos[0]));
+}
+
 /**
  * \!brief Query the available channel maps
  * \param pcm PCM handle to query
@@ -7415,6 +7422,10 @@ snd_pcm_chmap_t *snd_pcm_get_chmap(snd_pcm_t *pcm)
  */
 int snd_pcm_set_chmap(snd_pcm_t *pcm, const snd_pcm_chmap_t *map)
 {
+	const snd_pcm_chmap_t *oldmap = snd_pcm_get_chmap(pcm);
+	if (oldmap && chmap_equal(oldmap, map))
+		return 0;
+
 	if (!pcm->ops->set_chmap)
 		return -ENXIO;
 	return pcm->ops->set_chmap(pcm, map);