Re: [PATCH RFT] regulator: max8972: Fix setting ramp delay

From: Axel Lin
Date: Mon May 30 2016 - 04:52:18 EST

2016-05-30 16:48 GMT+08:00 Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>:
> On 05/29/2016 01:16 PM, Axel Lin wrote:
>> Current code can set ramp delay to a wrong setting that the return value
>> from .set_voltage_time_sel is not enough for proper delay.
> I don't understand what yo wanted to say here. What wrong setting is
> possible? Why do you mention set_voltage_time_sel() here?
> Can you elaborate?
> The only difference I spotted is how you round up the ramp_delay values.

Assume rdev->constraints->ramp_delay is 20000.

Original code will set MAX8973_RAMP_12mV_PER_US.

However, in regulator_set_voltage_time_sel()
return DIV_ROUND_UP(abs(new_volt - old_volt), ramp_delay);

This return value is not enough if the device is using MAX8973_RAMP_12mV_PER_US