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ALSA: usb: handle descriptor with SYNC_NONE illegal value

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The M-Audio Transit exposes an interface with a SYNC_NONE attribute.
This is not a valid value according to the USB audio classspec. However
there is a sync endpoint associated to this record. Changing the logic to
try to use this sync endpoint allows for seamless transitions between
altset 2 and altset 3. If any errors happen, the behavior remains the same.

$ more /proc/asound/card1/stream0
M-Audio Transit USB at usb-0000:00:14.0-2, full speed : USB Audio

Playback:
  Status: Stop
  Interface 1
    Altset 1
    Format: S24_3LE
    Channels: 2
    Endpoint: 3 OUT (ADAPTIVE)
    Rates: 48001 - 96000 (continuous)
  Interface 1
    Altset 2
    Format: S24_3LE
    Channels: 2
    Endpoint: 3 OUT (NONE)
    Rates: 8000 - 48000 (continuous)
  Interface 1
    Altset 3
    Format: S16_LE
    Channels: 2
    Endpoint: 3 OUT (ASYNC)
    Rates: 8000 - 48000 (continuous)

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Pierre-Louis Bossart 2015-08-14 17:19:43 -05:00 committed by Takashi Iwai
parent 630184477e
commit 395ae54bd8
1 changed files with 16 additions and 2 deletions
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18
sound/usb/pcm.c
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@ -412,10 +412,17 @@ static int set_sync_endpoint(struct snd_usb_substream *subs,
if (altsd->bNumEndpoints < 2)
return 0;
if ((is_playback && attr != USB_ENDPOINT_SYNC_ASYNC) ||
if ((is_playback && (attr == USB_ENDPOINT_SYNC_SYNC ||
attr == USB_ENDPOINT_SYNC_ADAPTIVE)) ||
(!is_playback && attr != USB_ENDPOINT_SYNC_ADAPTIVE))
return 0;
/*
* In case of illegal SYNC_NONE for OUT endpoint, we keep going to see
* if we don't find a sync endpoint, as on M-Audio Transit. In case of
* error fall back to SYNC mode and don't create sync endpoint
*/
/* check sync-pipe endpoint */
/* ... and check descriptor size before accessing bSynchAddress
because there is a version of the SB Audigy 2 NX firmware lacking
@ -429,6 +436,8 @@ static int set_sync_endpoint(struct snd_usb_substream *subs,
get_endpoint(alts, 1)->bmAttributes,
get_endpoint(alts, 1)->bLength,
get_endpoint(alts, 1)->bSynchAddress);
if (is_playback && attr == USB_ENDPOINT_SYNC_NONE)
return 0;
return -EINVAL;
}
ep = get_endpoint(alts, 1)->bEndpointAddress;
@ -439,6 +448,8 @@ static int set_sync_endpoint(struct snd_usb_substream *subs,
"%d:%d : invalid sync pipe. is_playback %d, ep %02x, bSynchAddress %02x\n",
fmt->iface, fmt->altsetting,
is_playback, ep, get_endpoint(alts, 0)->bSynchAddress);
if (is_playback && attr == USB_ENDPOINT_SYNC_NONE)
return 0;
return -EINVAL;
}
@ -450,8 +461,11 @@ static int set_sync_endpoint(struct snd_usb_substream *subs,
implicit_fb ?
SND_USB_ENDPOINT_TYPE_DATA :
SND_USB_ENDPOINT_TYPE_SYNC);
if (!subs->sync_endpoint)
if (!subs->sync_endpoint) {
if (is_playback && attr == USB_ENDPOINT_SYNC_NONE)
return 0;
return -EINVAL;
}
subs->data_endpoint->sync_master = subs->sync_endpoint;