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authorLuke Ross <luke@lukeross.name>2006-08-29 10:46:32 +0200
committerJaroslav Kysela <perex@suse.cz>2006-09-23 10:44:58 +0200
commita79eee8d3d8a80c37d235e1181d67c3705c7bbfe (patch)
tree1a0618e6aba24c6ca10d5822bc08c03219d794ee /sound/usb/usbaudio.c
parent9f458e7fb5b92385d348fb6039ba7211a6d6ba6e (diff)
downloadlinux-2.6.34-ux500-a79eee8d3d8a80c37d235e1181d67c3705c7bbfe.tar.gz
[ALSA] Support for non-standard rates in USB audio driver
There's at least one USB audio chipset out there which supports only one non-standard rate (ID 0e6a:0310 supports 46875Hz). There's a few other patches for this card which are unsatisfactory because they attempt to map this rate to 44.1k leading to sound distortion. The patch below uses SNDRV_PCM_RATE_KNOT to properly support the non-standard rates where they are available. Signed-off-by: Luke Ross <luke@lukeross.name> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Jaroslav Kysela <perex@suse.cz>
Diffstat (limited to 'sound/usb/usbaudio.c')
-rw-r--r--sound/usb/usbaudio.c46
1 files changed, 46 insertions, 0 deletions
diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index 087f9b64d8a..664dd4c21e6 100644
--- a/sound/usb/usbaudio.c
+++ b/sound/usb/usbaudio.c
@@ -123,6 +123,7 @@ struct audioformat {
unsigned int rate_min, rate_max; /* min/max rates */
unsigned int nr_rates; /* number of rate table entries */
unsigned int *rate_table; /* rate table */
+ unsigned int needs_knot; /* any unusual rates? */
};
struct snd_usb_substream;
@@ -1759,6 +1760,9 @@ static int check_hw_params_convention(struct snd_usb_substream *subs)
}
channels[f->format] |= (1 << f->channels);
rates[f->format] |= f->rates;
+ /* needs knot? */
+ if (f->needs_knot)
+ goto __out;
}
/* check whether channels and rates match for all formats */
cmaster = rmaster = 0;
@@ -1799,6 +1803,38 @@ static int check_hw_params_convention(struct snd_usb_substream *subs)
return err;
}
+/*
+ * If the device supports unusual bit rates, does the request meet these?
+ */
+static int snd_usb_pcm_check_knot(struct snd_pcm_runtime *runtime,
+ struct snd_usb_substream *subs)
+{
+ struct list_head *p;
+ struct snd_pcm_hw_constraint_list constraints_rates;
+ int err;
+
+ list_for_each(p, &subs->fmt_list) {
+ struct audioformat *fp;
+ fp = list_entry(p, struct audioformat, list);
+
+ if (!fp->needs_knot)
+ continue;
+
+ constraints_rates.count = fp->nr_rates;
+ constraints_rates.list = fp->rate_table;
+ constraints_rates.mask = 0;
+
+ err = snd_pcm_hw_constraint_list(runtime, 0,
+ SNDRV_PCM_HW_PARAM_RATE,
+ &constraints_rates);
+
+ if (err < 0)
+ return err;
+ }
+
+ return 0;
+}
+
/*
* set up the runtime hardware information.
@@ -1861,6 +1897,8 @@ static int setup_hw_info(struct snd_pcm_runtime *runtime, struct snd_usb_substre
SNDRV_PCM_HW_PARAM_CHANNELS,
-1)) < 0)
return err;
+ if ((err = snd_usb_pcm_check_knot(runtime, subs)) < 0)
+ return err;
}
return 0;
}
@@ -2406,6 +2444,7 @@ static int parse_audio_format_rates(struct snd_usb_audio *chip, struct audioform
unsigned char *fmt, int offset)
{
int nr_rates = fmt[offset];
+ int found;
if (fmt[0] < offset + 1 + 3 * (nr_rates ? nr_rates : 2)) {
snd_printk(KERN_ERR "%d:%u:%d : invalid FORMAT_TYPE desc\n",
chip->dev->devnum, fp->iface, fp->altsetting);
@@ -2428,6 +2467,7 @@ static int parse_audio_format_rates(struct snd_usb_audio *chip, struct audioform
return -1;
}
+ fp->needs_knot = 0;
fp->nr_rates = nr_rates;
fp->rate_min = fp->rate_max = combine_triple(&fmt[8]);
for (r = 0, idx = offset + 1; r < nr_rates; r++, idx += 3) {
@@ -2436,13 +2476,19 @@ static int parse_audio_format_rates(struct snd_usb_audio *chip, struct audioform
fp->rate_min = rate;
else if (rate > fp->rate_max)
fp->rate_max = rate;
+ found = 0;
for (c = 0; c < (int)ARRAY_SIZE(conv_rates); c++) {
if (rate == conv_rates[c]) {
+ found = 1;
fp->rates |= (1 << c);
break;
}
}
+ if (!found)
+ fp->needs_knot = 1;
}
+ if (fp->needs_knot)
+ fp->rates |= SNDRV_PCM_RATE_KNOT;
} else {
/* continuous rates */
fp->rates = SNDRV_PCM_RATE_CONTINUOUS;