On Wed, Jan 14, 2015 at 10:36 AM, Doug Anderson <dianders at chromium.org> wrote: > Sonny, > >> Chris, it looks like you swapped the set and the clear of this bit, >> and you're relying on the fact that the i2c transaction takes a >> certain amount of time after the RTC_GET_TIME BIT is set. I'm not >> sure how long it actually takes, but why not just put in a usleep() >> for the minimum wait time? > > I think we are safe. > > At 400kHz (the max speed of this part) each bit can be transferred no > faster than 2.5us. In order to do a valid i2c transaction we need to > _at least_ write the address of the device and the data onto the bus, > which is 16 bits. 16 * 2.5us = 40us. That's above the 31.25us > > Personally I think what Chris has is fine, with the comment. Ok, I'm fine with that if we're sure it's slow enough. Comment explaining would certainly help. > > -Doug
