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ALSA: usb-audio: Filter out unsupported sample rates on Focusrite devices 

commit 1c82679258 upstream.

Many Focusrite devices supports a limited set of sample rates per
altsetting. These includes audio interfaces with ADAT ports:
 - Scarlett 18i6, 18i8 1st gen, 18i20 1st gen;
 - Scarlett 18i8 2nd gen, 18i20 2nd gen;
 - Scarlett 18i8 3rd gen, 18i20 3rd gen;
 - Clarett 2Pre USB, 4Pre USB, 8Pre USB.

Maximum rate is exposed in the last 4 bytes of Format Type descriptor
which has a non-standard bLength = 10.

Tested-by: Alexey Skobkin <skobkin-ru@ya.ru>
Signed-off-by: Alexander Tsoy <alexander@tsoy.me>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200418175815.12211-1-alexander@tsoy.me
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexander Tsoy 2020-04-18 20:58:15 +03:00 committed by Greg Kroah-Hartman
parent d5cd821536
commit 387039b250
1 changed files with 52 additions and 0 deletions
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52
sound/usb/format.c
View File

@ -226,6 +226,52 @@ static int parse_audio_format_rates_v1(struct snd_usb_audio *chip, struct audiof
return 0;
}
/*
* Many Focusrite devices supports a limited set of sampling rates per
* altsetting. Maximum rate is exposed in the last 4 bytes of Format Type
* descriptor which has a non-standard bLength = 10.
*/
static bool focusrite_valid_sample_rate(struct snd_usb_audio *chip,
struct audioformat *fp,
unsigned int rate)
{
struct usb_interface *iface;
struct usb_host_interface *alts;
unsigned char *fmt;
unsigned int max_rate;
iface = usb_ifnum_to_if(chip->dev, fp->iface);
if (!iface)
return true;
alts = &iface->altsetting[fp->altset_idx];
fmt = snd_usb_find_csint_desc(alts->extra, alts->extralen,
NULL, UAC_FORMAT_TYPE);
if (!fmt)
return true;
if (fmt[0] == 10) { /* bLength */
max_rate = combine_quad(&fmt[6]);
/* Validate max rate */
if (max_rate != 48000 &&
max_rate != 96000 &&
max_rate != 192000 &&
max_rate != 384000) {
usb_audio_info(chip,
"%u:%d : unexpected max rate: %u\n",
fp->iface, fp->altsetting, max_rate);
return true;
}
return rate <= max_rate;
}
return true;
}
/*
* Helper function to walk the array of sample rate triplets reported by
* the device. The problem is that we need to parse whole array first to
@ -262,6 +308,11 @@ static int parse_uac2_sample_rate_range(struct snd_usb_audio *chip,
}
for (rate = min; rate <= max; rate += res) {
/* Filter out invalid rates on Focusrite devices */
if (USB_ID_VENDOR(chip->usb_id) == 0x1235 &&
!focusrite_valid_sample_rate(chip, fp, rate))
goto skip_rate;
if (fp->rate_table)
fp->rate_table[nr_rates] = rate;
if (!fp->rate_min || rate < fp->rate_min)
@ -276,6 +327,7 @@ static int parse_uac2_sample_rate_range(struct snd_usb_audio *chip,
break;
}
skip_rate:
/* avoid endless loop */
if (res == 0)
break;