linux1394-devel

Iso write function

[ACCARIE Jean-P. <ac...@cr...>]

Hi,

I have been following this mailing list since several months now
and I noticed that many people were requesting iso write function.
As I intend to develop some isochronous applications on top of
the Linux 1394 driver in the coming weeks I will also require
the iso write function (I planned to use an OHCI 1394 board
although I am not very familiar with OCHI specifications).
I'd like to know what is the current situation concerning 
iso write function:
1- I browsed the source code very quickly and didn't find
   anything whatever the level (ohci1394, ieee1394 or raw1394)
   Is this the same for pcilynx and aic5800?
2- I'd like to know if there is somebody already in charge of
   writing such iso writing function.
   If so, I'd like to know how I can contribute (coding, 
   debugging,...) although I am very busy as everybody there;-)
3- Is there somebody here who already coded some basic implementation
   even if it has not been registered within CVS and that could be 
   taken as a basis?
4- I was also wondering why this feature was missing: is there
   any tricky issues?

Thanks
Jean-Paul

Re: Iso write function

[Andreas B. <and...@mu...>]

On Tue, Apr 25, 2000 at 03:31:32PM +0200, ACCARIE Jean-Paul wrote:
> I'd like to know what is the current situation concerning 
> iso write function:
> 1- I browsed the source code very quickly and didn't find
>    anything whatever the level (ohci1394, ieee1394 or raw1394)
>    Is this the same for pcilynx and aic5800?

It seems simple to implement iso sending for the PCILynx hardware.  I
guess OHCI isn't that hard either.  

> 2- I'd like to know if there is somebody already in charge of
>    writing such iso writing function.
>    If so, I'd like to know how I can contribute (coding, 
>    debugging,...) although I am very busy as everybody there;-)

I'd do the PCILynx part anyway.

> 3- Is there somebody here who already coded some basic implementation
>    even if it has not been registered within CVS and that could be 
>    taken as a basis?

The subsystem supports different types of packets to send (iso is one
of them), but e.g. PCILynx just assumes async packets.  The hardware
part should be implemented first and be tested.

> 4- I was also wondering why this feature was missing: is there
>    any tricky issues?

Management and allocation of resources (and reallocation after bus
reset).  While I'm implementing GUID collecting here I found out it's
not that hard to do subsystem initiated transactions
(i.e. transactions which were not requested by a process).

-- 
 Andreas E. Bombe <and...@mu...>    DSA key 0x04880A44
http://home.pages.de/~andreas.bombe/    http://linux1394.sourceforge.net/

Re: Iso write function

[Sebastien R. <Seb...@sy...>]

>1- I browsed the source code very quickly and didn't find
>   anything whatever the level (ohci1394, ieee1394 or raw1394)
>   Is this the same for pcilynx and aic5800?

That's normal, no support yet for ohci.

>2- I'd like to know if there is somebody already in charge of
>   writing such iso writing function.
>   If so, I'd like to know how I can contribute (coding, 
>   debugging,...) although I am very busy as everybody there;-)

AFAIK, nobody is working on this for the ohci driver. I would
welcome any patch/suggestion people may have.

>4- I was also wondering why this feature was missing: is there
>   any tricky issues?

I have not really looked into it yet. I don't think it would
be that difficult, but I have other priorities right now.

-- 
Sebastien Rougeaux
RSISE, The Australian National University