Re: xhci_hcd error Transfer event TRB DMA ptr not part of current TD ep_index 8 comp_code 1

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Hi Alistair,

> There are some small differences in packet ordering, however the first
> major difference is an isochronous in packet where the Live2 returns
> "URB status: No such file or directory (-ENOENT) (-2)".
>
> Devin, I'm try to learn a bit about USB and the Live2 protocol, however I'm
> not sure how far I'll get.  Are you able to offer any hints on what to do
> next?

I'm sorry if I'm asking something already answered in your original
description of the problems - but have you confirmed the device works
properly on a system with a standard EHCI controller (as opposed to
XHCI)?

The reason I ask is because that the cx231xx driver is pretty unstable
in general, and I'm wondering if perhaps you're just hitting some
issue completely unrelated to the recent XHCI problems (which
obviously needed to be addressed in order for you to get this far into
testing).

If you haven't tried it yet on a standard ECHI controller because you
don't have one in your PC, it might be worth spending the $20 to buy a
PCI card with an USB 2.0 host controller on it for testing.

It's also worth mentioning that the process you're exercising isn't
just the code path for device insertion.  The udev process and
PulseAudio will both try to connect to the device as soon as the
underlying device nodes appear, so it's possible there is some race
condition where the device is being accessed and registers are being
poked before initialization is complete.  I cannot say for certain
this would be an issue with cx231xx, but I've definitely seen it with
other V4L2 drivers.  That might also explain why you see different
behavior at boot - the driver loads early enough in the boot process
such that initialization completes before processes like udev and
pulseaudio get a chance to interact with it.

Devin

-- 
Devin J. Heitmueller - Kernel Labs
http://www.kernellabs.com
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