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Commit ebfc594c02148b6a85c2f178cf167a44a3c3ce10

Authored by Daniel Mack
Committed by Takashi Iwai
1 parent 13627549f3
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

ALSA: snd-usb: try harder to find USB_DT_CS_ENDPOINT 

The USB_DT_CS_ENDPOINT class-specific endpoint descriptor is usually
stuffed directly after the standard USB endpoint descriptor, and this is
where the driver currently expects it to be.

There are, however, devices in the wild that have it the other way
around in their descriptor sets, so the USB_DT_CS_ENDPOINT comes
*before* the standard enpoint. Devices known to implement it that way
are "Sennheiser BTD-500" and Plantronics USB headsets.

When the driver can't find the USB_DT_CS_ENDPOINT, it won't be able to
change sample rates, as the bitmask for the validity of this command is
storen in bmAttributes of that descriptor.

Fix this by searching the entire interface instead of just the extra
bytes of the first endpoint, in case the latter fails.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Reported-and-tested-by: Torstein Hegge <hegge@resisty.net>
Reported-and-tested-by: Yves G <alsa-user@vivigatt.com>
Cc: stable@kernel.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Showing 1 changed file with 8 additions and 0 deletions Side-by-side Diff

... ... @@ -393,6 +393,14 @@
393 393 if (!csep && altsd->bNumEndpoints >= 2)
394 394 csep = snd_usb_find_desc(alts->endpoint[1].extra, alts->endpoint[1].extralen, NULL, USB_DT_CS_ENDPOINT);
395 395  
  396 + /*
  397 + * If we can't locate the USB_DT_CS_ENDPOINT descriptor in the extra
  398 + * bytes after the first endpoint, go search the entire interface.
  399 + * Some devices have it directly *before* the standard endpoint.
  400 + */
  401 + if (!csep)
  402 + csep = snd_usb_find_desc(alts->extra, alts->extralen, NULL, USB_DT_CS_ENDPOINT);
  403 +
396 404 if (!csep || csep->bLength < 7 ||
397 405 csep->bDescriptorSubtype != UAC_EP_GENERAL) {
398 406 snd_printk(KERN_WARNING "%d:%u:%d : no or invalid"