[alsa-devel] Allocating buffers for USB transfers (again)

[Daniel Mack]

On Fri, Aug 12, 2011 at 1:50 AM, Matěj Laitl <matej at laitl.cz> wrote:
> On 12. 8. 2011 Daniel Mack wrote:
>> > This patch actually makes the sound playback _worse_. Now I get strange
>> > squawks where previously at least first seconds of a song sounded
>> > normally.
>> >
>> > However, I no longer get "zero length buffer submitted" or that "...
>> > Weird." debug messages, only several megabytes of: (should I post these
>> > somewhere?)
>> >
>> > xhci_hcd 0000:05:00.0: Giveback URB ffff880114cec000, len = 880,
>> > expected = 1000, status = -115
>> > xhci_hcd 0000:05:00.0: Giveback URB ffff880114740000, len = 352,
>> > expected = 1000, status = -115
>> > xhci_hcd 0000:05:00.0: underrun event on endpoint
>>
>> Might be the hardware doesn't like this. As I said, the patch is blindly
>> written and I couldn't test it. Did you test this on a EHCI port as well?
>
> Good point, this patch distorts the playback also on the EHCI port. (the
> playback seems to be 10 times slower than it should be)

And it is only this *last* patch that causes it, yes?

If that is the case, we need empty subframes in the middle of urbs,
and we need to figure a way how to teach the XHCI driver to cope with
that, too.


Daniel