on patch "DVB: add firesat driver" in staging.git

Stefan Richter stefanr at s5r6.in-berlin.de
Sat Jun 14 21:55:19 UTC 2008

Hi list,

since the mentioned driver interfaces with the drivers/ieee1394 
subsystem, I had a brief look at it today.  There is a number of 
stylistic issues and kernel API issues to work on, like
   - use of a semaphore,
   - struct types with bitfields for what appears to be on-the-wire data,
   - camel case names,
   - "#define BYTE   unsigned char" and friends,
   - stale duplicated code like "BUG_ON(in_interrupt())" or all
     references to ohci1394 which seem unnecessary,
   - homebrewed down_timeout,
   - comment style not as in linux kernel.
So there is a number of small things that even people who don't have 
respective hardware _could_ work on.  But read on before you start 
cleaning those up:

A bigger issue is the interfacing with drivers/ieee1394.  As most of the 
subscribers probably know, Linux now contains two IEEE 1394 stacks which 
are entirely independent of each other.  The newer one is 
drivers/firewire and is meant to replace drivers/ieee1394 once it is 
stable enough and has all the necessary features.

This means that firesat needs to be ported to the new stack eventually. 
The question remains if that should be done before mainline submission 
or after.  I tend to the latter, even if merely because ieee1394 and 
firewire subsystem maintenance and development is chronically 
under-staffed, hence bandwidth for mentoring and review of new additions 
like firesat is low.  (It looks like an IEC 61883 implementation, one of 
the FireWire areas I myself am less familiar with.  Therefore I also 
didn't pressure Ben to look into the firewire stack when he discussed 
ieee1394 API issues on linux1394-devel.)

So, because of the need to port it to a different in-kernel API 
eventually, current firesat's ieee1394 interfacing code does not have to 
be brought to perfection anymore.  Instead, work on it should either 
have the goal of later gradual movement to the firewire stack (i.e. make 
it possible to build firesat for ieee1394 or for firewire) _or_ should 
port it over to firewire right away (something which obviously nobody 
else wanted to undertake so far).

I suppose which way to proceed depends a lot on what is going on at the 
DVB side and on who is picking up the work.
Stefan Richter
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