[alsa-devel] [PATCH 39/39] bebob: Add support for M-Audio special Firewire series

[Stefan Richter]

On Feb 28 Takashi Sakamoto wrote:
> This commit allows this driver to support some models which M-Audio produces
> with DM1000 but its firmware is special. They are:
>  - Firewire 1814
>  - ProjectMix I/O
[...]
> M-Audio special firmware quirks:
[...]
>  - They often handle requests without responding. In this reason, this driver
>    often fail to handle them correctly.
[...]
> An fallback at timeout in the operations for CMP was already
> added by previous commit. But for isochronous resource management, no fallbacks
> are added. Further works are needed for Linux Firewire Subsystem.

We could add a workaround in drivers/firewire/core-iso.c which works
similar to your CMP related workaround in patch 18/39.  I.e., after a
timed-out lock request to CHANNELS_AVAILABLE or BANDWIDTH_AVAILABLE,
perform a read request to see what happened.  Like your CMP workaround,
this is fragile because it races with concurrent lock requests.

Or we could add a workaround in drivers/firewire/core-card.c which would
attempt to make the local node root node (and thereby IRM) if it detects
that an M-Audio device is currently IRM.

Not sure what's better.
-- 
Stefan Richter
-=====-====- --== ----=
http://arcgraph.de/sr/