Hi Mark, On Mon, 16 Nov 2015 10:55:58 +0000 Mark Brown <broonie@xxxxxxxxxx> wrote: > On Mon, Nov 16, 2015 at 09:56:32AM +0100, Boris Brezillon wrote: > > > +++ b/drivers/regulator/pwm-regulator.c > > @@ -56,7 +56,7 @@ static int pwm_regulator_set_voltage_sel(struct regulator_dev *rdev, > > int dutycycle; > > int ret; > > > > - pwm_reg_period = pwm_get_period(drvdata->pwm); > > + pwm_reg_period = pwm_get_default_period(drvdata->pwm); > > > > dutycycle = (pwm_reg_period * > > drvdata->duty_cycle_table[selector].dutycycle) / 100; > > It's not clear to me that we're not looking for the current period here > or in the other use. Won't configuring based on a period other than the > one that has been set give the wrong answer? Hm, maybe that's naming problem. What I call the 'default' period here is actually the period configured in your board file (using a PWM lookup table) or your DT. This value represent the period requested by the PWM user not a default value specified by the PWM chip driver. The reason we're not using the 'current' period value is because it may have been set by the bootloader, and may be inappropriate for our use case (ie. the period may be to small to represent the different voltages). ITOH, we're using the current period value when calculating the current voltage, because we want to get the correct voltage value, and the PWM device may still use the configuration set by the bootloader (not the default one specified in your board or DT files). I hope this clarifies the differences between the current and default period, and why we should use the default value here. Best Regards, Boris -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
