Re: [BUG, bisected] atmel_spi: hard lockups in transfer

[Ben Nizette <bn@niasdigital.com>]

On Wed, 2008-04-09 at 14:00 +0200, Marc Pignat wrote:
> > Ben Nizette <bn@niasdigital.com> wrote:
> > 
> > As I say, this is present in .24+ so any fix will be a stable candidate
> > as well as .25 material (if we haven't missed the boat by then).
> mainline .24+ is not affected (linux-2.6.24.3.atmel.3.tar.bz2 is).
> 

Hmm, I was sure I'd seen reports on vanilla kernels too.  I've confirmed
it's present in avr32-2.6.git/master/HEAD and the patch is in mainline
so I would expect the bug to be there, even if the symptoms are lacking.
Adding #define DEBUG to the top of atmel_spi.c changed the point at
which the bug triggers, there may be a similar coincidental
alignment-of-the-planets in mainline which means this bug doesn't
trigger at all.

Hmm..

> > 
> > I'm afraid I don't have much time to look at this right now...but I'll
> > see what I can do. It's strange that I never noticed this problem
> > myself -- I did see some overrun issues, but I blamed it on the
> > throughput improvements and just reduced the speed slightly.
> This patch seems to have problems at least on avr32, since this is only
> a speed-up patch, we should revert them.

I would think that's a good move in the short term but obviously speed
is a good thing and I would really like to see us get to the bottom of
this :-)

--Ben.