[alsa-devel] [PATCH 3/3] Add handling CMP output connection

[Takashi Sakamoto]

I'm sorry but I correct what I said:

 > Actually the target device seems to update the max payload size after
 > host connects to CMP output plug because its initial value is zero.
 > Then we already allocate isochronous resources and isochronous packet
 > to host system. I don't think it better to reallocate them after the
 > connecting.

We don't allocate buffer for isochronous packet yet when connecting CMP 
output plug. Then we just gain isochronous resource.

Anyway I don't think it better to reallocate isochronous resource.


Regards

Takashi Sakamoto

(Apr 29 2013 18:25), Takashi Sakamoto wrote:
> Clemens,
>
>  > The specification was written for the general case where the device
>  > that creates the connection might be different from the transmitting
>  > and receiving devices.  In that case, the payload size is needed for
>  > correct bandwidth allocation.
>
> I'm sure that the general case.
>
>  > In our case, the Linux PC does not have plugs that could be accessed
>  > by anybody else.
>
> I'm sure that host system (Linux PC) doesn't have no plugs.
>
>  >  (And I'm not sure if the value set by the Fireworks
>  > firmware is correct enough so that we'd want to use it.)
>
> With my Fireworks device, it always report 0, it means 1024 bytes for
> max payload size for output plug. But I'm not sure that it always report
> the same value. Especially at 192.0 kHz, the payload size is over 1024
> bytes but my device supports up to 96.0 kHz...
>
> Actually the target device seems to update the max payload size after
> host connects to CMP output plug because its initial value is zero. Then
> we already allocate isochronous resources and isochronous packet to host
> system. I don't think it better to reallocate them after the connecting.
>
> It's reasonable to ignore the payload field in any processing.
>
>
> Regards
>
> Takashi Sakamoto
>
> (Apr 29 2013 15:30), Clemens Ladisch wrote:
>> Takashi Sakamoto wrote:
>>> Then I have a question about handling payload field. In specification,
>>> "The payload field shall specify the maximum number of quadlets that
>>> may be transmitted in a single isochronous packet for this plug" but
>>> actually cheking this field seems to make no sense because there is no
>>> checking process in the procedure. I think I can do nothing for
>>> payload field.
>>
>> The specification was written for the general case where the device that
>> creates the connection might be different from the transmitting and
>> receiving devices.  In that case, the payload size is needed for correct
>> bandwidth allocation.
>>
>> In our case, the Linux PC does not have plugs that could be accessed by
>> anybody else.  (And I'm not sure if the value set by the Fireworks
>> firmware is correct enough so that we'd want to use it.)
>>
>>
>> Regards,
>> Clemens