[PATCH v6] i2c: rk3x: adjust the LOW divison based on characteristics of SCL

[Max Schwarz]

Hi Addy,

On Tuesday 14 October 2014 at 14:09:21, Addy Ke wrote:
> As show in I2C specification:
> - Standard-mode: the minimum HIGH period of the scl clock is 4.0us
>                  the minimum LOW period of the scl clock is 4.7us
> - Fast-mode: the minimum HIGH period of the scl clock is 0.6us
>              the minimum LOW period of the scl clock is 1.3us
> 
> I have measured i2c SCL waveforms in fast-mode by oscilloscope
> on rk3288-pinky board. the LOW period of the scl clock is 1.3us.
> It is so critical that we must adjust LOW division to increase
> the LOW period of the scl clock.
> 
> Thanks Doug for the suggestion about division formulas.
> 
> Tested-by: Heiko Stuebner <heiko at sntech.de>
> Reviewed-by: Doug Anderson <dianders at chromium.org>
> Tested-by: Doug Anderson <dianders at chromium.org>
> Signed-off-by: Addy Ke <addy.ke at rock-chips.com>

Reviewed-by: Max Schwarz <max.schwarz at online.de>
Tested-by: Max Schwarz <max.schwarz at online.de>

Cheers,
  Max