Addy, On Tue, Dec 2, 2014 at 6:37 PM, Addy Ke <addy.ke at rock-chips.com> wrote: > high_ns calculated from the low division of CLKDIV register is the sum > of actual measured high_ns and rise_ns. The rise time which related to > external pull-up resistor can be up to the maximum rise time in I2C spec. > > In my test, if external pull-up resistor is 4.7K, rise_ns is about > 700ns. So the actual measured high_ns is about 3900ns, which is less > than 4000ns(the minimum high_ns in I2C spec). > > To fix this bug, min_low_ns should include fall time and min_high_ns > should include rise time too. > > This patch merged the patch that Doug submitted to chromium, which > can get the rise and fall times for signals from the device tree. > This allows us to more accurately calculate timings. see: > https://chromium-review.googlesource.com/#/c/232774/ > > Signed-off-by: Addy Ke <addy.ke at rock-chips.com> > --- > Changes in v2: > - merged the patch that Doug submitted to chromium > > Documentation/devicetree/bindings/i2c/i2c-rk3x.txt | 10 ++++ > drivers/i2c/busses/i2c-rk3x.c | 55 +++++++++++++++------- > 2 files changed, 47 insertions(+), 18 deletions(-) This looks good to me. Thank you for spinning. Reviewed-by: Doug Anderson <dianders at chromium.org>
