[PATCH AUTOSEL 5.2 037/185] ALSA: usb-audio: Skip bSynchAddress endpoint check if it is invalid

Sasha Levin
2019-09-22T19:28:38Z

From: Ard van Breemen <ard@kwaak.net>

[ Upstream commit 1b34121d9f26d272b0b2334209af6b6fc82d4bf1 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/usb/pcm.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index e4bbf79de956e..33cd26763c0ee 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -457,6 +457,7 @@ 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,
--
2.20.1