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

From: Wolfram Sang
Date: Thu Sep 08 2016 - 16:19:08 EST


On Sat, Aug 27, 2016 at 03:39:30PM +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.
>
> Signed-off-by: Zhuo-hao Lee <zhuo-hao.lee@xxxxxxxxx>

Applied to for-current, thanks!

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