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ALSA: usb-audio: Skip bSynchAddress endpoint check if it is invalid 

The Linux kernel assumes that get_endpoint(alts,0) and
get_endpoint(alts,1) are eachothers feedback endpoints.
To reassure that validity it will test bsynchaddress to comply with that
assumption. But if the bsyncaddress is 0 (invalid), it will flag that as
a wrong assumption and return an error.
Fix: Skip the test if bSynchAddress is 0.
Note: those with a valid bSynchAddress should have a code quirck added.

Signed-off-by: Ard van Breemen <ard@kwaak.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Ard van Breemen 2019-08-02 13:52:14 +02:00 committed by Takashi Iwai
parent f7f5301814
commit 1b34121d9f
1 changed files with 1 additions and 0 deletions
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1
sound/usb/pcm.c
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@ -456,6 +456,7 @@ static int set_sync_endpoint(struct snd_usb_substream *subs,
}
ep = get_endpoint(alts, 1)->bEndpointAddress;
if (get_endpoint(alts, 0)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
get_endpoint(alts, 0)->bSynchAddress != 0 &&
((is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress | USB_DIR_IN)) ||
(!is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress & ~USB_DIR_IN)))) {
dev_err(&dev->dev,