linux-kernel - Re: isochronous receives?

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Message-ID: <4570045D.40100@s5r6.in-berlin.de>
Date:	Fri, 01 Dec 2006 11:30:53 +0100
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	Keith Curtis <Keith.Curtis@...eo.com>
CC:	Robert Crocombe <rcrocomb@...il.com>,
	linux1394-devel <linux1394-devel@...ts.sourceforge.net>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: isochronous receives?

Keith Curtis wrote:
> I never resolved the problem. I turned on the excessive debugging output, but it 
> didn't print out info about receiving packets or interrupts. My test 
> app claimed there were no packets received although the bus analyzer 
> showed lots of packets going by.  
> 
> If I can help out, let me know, but I'm not sure where to start at this point.
...
> -----Original Message-----
> From: Robert Crocombe [mailto:rcrocomb@...il.com]
> Sent: Tuesday, November 28, 2006 4:59 PM
...
> Did you ultimately have any success getting this going?  Funnily
> enough, when I tested isochronous stuff in July, I just did iso
> transmit since I figured receives *must* be working since everyone has
> camcorders and whatnot.  My currently my iso xmit stuff does appear to
> be working, but iso receives are not.
> 
> I have a Firespy and no reason not to trust it, so I can see the junk
> I'm spewing out.  I've tried transmitting on channels 4 and 63 (per
> your advice), but neither works for me.  I suppose it could my
> stuff... nah.

I don't know much about the mechanisms, but I suppose there could be one
of the following causes:
 - The IR DMA context was never set up for the respective channel in the
   first place.
 - The context was set up but the interrupt event masks weren't switched
   on, i.e. IntMask as per OHCI clause 6.2 and isoRecvIntMask as per
   clause 6.3.2.
 - The context and masks were set up, but then one or both of the masks
   were switched off again, similar to the bus reset bug which Robert
   reported: http://bugzilla.kernel.org/show_bug.cgi?id=7569
-- 
Stefan Richter
-=====-=-==- ==-- ----=
http://arcgraph.de/sr/
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