[alsa-devel] Kernel: snd-usb-audio: probe of 2-2:1.0 failed with error -5

Linus Torvalds torvalds at linux-foundation.org
Tue Nov 29 17:58:51 CET 2011

On Tue, Nov 29, 2011 at 4:52 AM, Nixbits Admin <admin at nixbits.org> wrote:
> While knowing that your time is precious and without wanting to making you
> spend more than what you may be able to spare for my problem; i would like
> ask you if you could take a look at this issue.
> https://forums.gentoo.org/viewtopic-p-6885908.html#6885908
> snd-usb-audio: probe of 2-2:1.0 failed with error -5

This is related to the line above it:

  Nov 29 07:21:21  kernel: skipping empty audio interface (v1)
  Nov 29 07:21:21  kernel: snd-usb-audio: probe of 2-3:1.0 failed with error -5

which in turn is because of a zero "bInCollection" value in the device
control header. I'm adding some sound people to the cc, in case
anybody has more clues about what's wrong with that particular device
- I don't personally have any real clue about usb audio.

As to your UHCI/EHCI confusion - it's actually a USB confusion. EHCI
was done as a add-on to UHCI (or OHCI), to the point where there is
both a UHCI *and* an EHCI controller involved (on the same silicon)
and they have this odd hand-over thing where one part (the UHCI part)
handles legacy devices, and then the new bolted-on EHCI part handles
the full USB-2.0 functionality.

So the UHCI/EHCI confusion is deep in the silicon itself. If you
attach a usb-1.1 device, it will be handed off to the UHCI part, if
you attach a 2.0 device it will be handled by the EHCI part of the
controller. Oh the wonders of crazy backwards compatibility hacks..


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