[alsa-devel] firewire-lib: an issue to generate packet with 'no data' in blocking mode

[Takashi Sakamoto]

Clemens,

I have a question about generate packet with 'no data' in blocking mode.
I think there is out of specification in current firewire-lib.

If this is a qurk for some devices, I'll prepare patches to switch
generating mode because BeBoB cannot sound with current firewire-lib. If
this is a bug, then I want to discuss which is better for firewire-lib.


In my understanding of IEC 61883-6, there are two ways:

1. generate 'empty packet' defined in IEC 61883-1
   - size of packet is 2 quadlets
   - FDF = sfc
   - packet includes just CIP headers

2. generate 'special non-empty packet' defined in IEC 61883-6
   - size of packet is following to blocking mode
   - FDF = 0xff ('NO-DATA' code)
   - packet includes dummy data

But current implementation is a strange combination of them.
 - size of packet is 2 (way 1)
 - FDF = 0xff (way 2)

I attach two patches. 'empty.patch' is for 1 and 'special.patch' is for 2.


Regards

Takashi Sakamoto
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