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

Wolfram Sang wsa at the-dreams.de
Mon Nov 10 06:58:52 PST 2014


On Tue, Oct 14, 2014 at 02:09:21PM +0800, 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>

Applied to for-next, thanks!

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