i2c speed up
vlado at moko.ksp.sk
Tue Dec 9 16:52:39 CET 2008
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Hi all i2c hackers,
(I've added Ben Dooks as the author of relevant code)
> I found the reason why the i2c is on the phone so slow.
> The phone uses the driver i2c-s3c2410.c
> And after each acces to i2c there is the function msleep(1).
> Which needs on the openmoko about 10ms.
Yes, I can confirm this. I'm connecting some prototype pointing device that
needs to access several i2c registers on each readout of current position
and having some 100ms delay here is really bad (both the delay as well as
limited readout frequency).
> I made a little patch for that and now i2c is quite fast.
> Maybe that should help someone. One I2C-Access needs now about ~0.6ms
> and before it was 10ms.
> I attached the patch.
With this patch I sometimes can't even boot my neo (gta02a6) :( but yes,
when it manages to fully boot it works much better. However, those udelays()
are most probably not really good for the rest of the system..
Is there anything that could be done to fix this? this limits i2c usability
a lot :(
> Kind regards,
> Matthias Katzengruber
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