Re: [PATCH v1] i2c: designware: save the preset value of DW_IC_SDA_HOLD

[Jarkko Nikula]

On 08/28/2016 03:31 PM, Andy Shevchenko wrote:
> On Sat, 2016-08-27 at 15:39 +0800, Zhuo-hao Lee wrote:
> > There are several ways to set the SDA hold time for i2c controller,
> > including: Device Tree, built-in device properties and ACPI. However,
> > if the SDA hold time is not specified by above method, we should
> > read the value, where it is preset by firmware, and save it to
> > sda_hold_time. This is needed because when i2c controller enters
> > runtime suspend, the DW_IC_SDA_HOLD value will be reset to chipset
> > default value. And during runtime resume, i2c_dw_init will be called
> > to reconfigure i2c controller. If sda_hold_time is zero, the chipset
> > default hold time will be used, that will be too short for some
> > platforms. Therefore, to have a better tolerance, the DW_IC_SDA_HOLD
> > value should be kept by sda_hold_time.
>
> Looks good to me.
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Acked-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>