1) Well , as i am using a embedded target the details of the usb host
controller is not available with me now .
i can share the information once it is available to me .
2) this problem comes only with usb high speed ,
if host is configured for usb full speed , this problem does not come .
3) the kernel is a bit relatively old , its 2.6.26 , but as it is a
embedded target ,
we cannot port latest new kernel right now .
4) there is some discussion of a patch , which i think has come in
2.6.34 kernel
the discussion is held here .
http://www.spinics.net/lists/alsa-devel/msg30421.html .
can this be a solution to my problem .
5) we are reading 8192 bytes from user space audio application in one shot .
how much data should be read ideally in one go ?
6) i am using oss calls (ioctls and read via /dev/dsp ) to fetch
audio data . can their be any difference in behaviour if we switch
to alsa apis in userspace .
Waiting for ur reply . thanx for ur time .
Regards
Amit Nagal
On Mon, Sep 6, 2010 at 2:39 PM, Clemens Ladisch <clemens@xxxxxxxxxx> wrote:
> Amit Nagal wrote:
>> i am trying to do digital audio streaming over usb audio class interface .
>>
>> when i stream audio , kernel produces these logs very frequently .
>>
>> ALSA sound/usb/usbaudio.c:351: frame 0 active: -18 .
>>
>> upon seeing documentation , -18 comes to be EXDEV (#define EXDEV
>> 18 /* Cross-device link */) .
>
> This error code is documented in Documentation/usb/error-codes.txt:
> | -EXDEV ISO transfer only partially completed
> | look at individual frame status for details
>
> Well, this _is_ the individual frame status.
>
> Anyway, a look at the source code shows that several HCDs use this code
> for frames that were not handled by the controller, probably because
> they were submitted too late.
>
> Which controller are you using?
>
> Is there anything that could cause the controller to skip frames, such
> as high traffic on the (PCI) bus?
>
>
> Regards,
> Clemens
>
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