[alsa-devel] USB asynchronous mode feedback format

Alex lee188 at singnet.com.sg
Thu Oct 14 08:25:09 CEST 2010

19.13 with the most sig 7 bits not used.


Sent from my iPhone

On Oct 14, 2010, at 1:57 PM, Julian Scheel <julian at jusst.de> wrote:

> Hi Alex,
> "Alex" <lee188 at singnet.com.sg> schrieb:
>> The current alsa rate feedback rate feedback format is
>> 12.13 in 4 bytes.  Clemens has a patch to make the rate
>> feedback format automatic such that it will work with
>> 10.14 16.16 or any other formats.  We are still testing the
>> patch put .  Currently with 12.13 format rate feedback
>> works well.
> How does it come that alsa uses 12.13? I don't see that mentioned in the specs?
> Is it right or left aligned in the 4 bytes?
>> For example, AT91SAM7 has a limitation of EP siE of 64
>> bytes for EP 3 used for ISO transfers.  There may also be
>> a limitation in that the Same EP number cannot be used
>> for both IN and OUT.
> Hm, I'm not sure about this. You think I should move the feedback pipe into it's own EP?
> I will recheck the At91SAM7 specs later, to see if I can find a note on such a limitation.
> Thanks,
> Julian

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