[i2c] Is review of AT91 patch pending?

Ronny Nilsson rln-i2c at arbetsmyra.dyndns.org
Fri Oct 19 10:26:20 CEST 2007


> > Here's an update of my AT91 bus driver with IRQ support.
> > Previously the best speed it could handle was in the range of
> > 30-50 kHz, any higher and transfer errors began occurring. This
> > has however changed. The attached patch can handle 400 kHz, even
> > on a loaded system!
> >

> I got this working on the 2.6.23-rc9 kernel (so many changes from
> rc3!).
> First results don't look good, sorry.
> I use one of our own i2c EEPROM filing system utility tools for the
> testing. It reads about 4K bytes from an EEPROM, and checks the
> CRC-32 of the data. This is my standard test as it quickly reveals
> any problems.

Hi
Very interesting that our results got completely different. I too made 
block reads from an eeprom but didn't get a single error in 400 kHz, 
no matter how hard I tried...

It's true that the GPIO driver will always be a better choice if 
reliability i crucial, however I'd still like to know why my system 
can run five times faster than yours. Would it be possible for you to 
send me your stress application and a diff of your entire 2.6.23-rc9 
kernel? (if so, send them privately of list). Which compiler version 
do you use?

Regards
/Ronny




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