On 18.01.2018 01:10, Brian Norris wrote: > On Wed, Jan 17, 2018 at 10:29:53AM +0200, Claudiu Beznea wrote: >> With these changes, if pwm-cells=1 then only PWM-channel will be parsed, > > I'm not sure if I'm understanding you correctly but...no. If cells is 1, > then your driver change just causes us not to parse correctly, and > everything fails. My bad, agree with you, will fail with pwm-cells=1. I forgot about: + if (args->args_count < PWM_ARGS_CNT_XLATE_PERIOD || + args->args_count > PWM_ARGS_CNT_XLATE_MAX) return ERR_PTR(-EINVAL); restriction. > >> if it is 2 PWM-channel and PWM-period will be parsed, if pwm-cells=3 >> then PWM-channel, PWM-period and PWM-flags will be parsed. >> In your driver you used to have only one cell because you wanted to allow >> user to give as argument only PWM channel, and you did not want a change >> of PWM period (and in of_xlate function you initialize pwm period with 0xffff >> value: this is why I changed the binding in patch 7 of this series, file > > It's not a matter of "allow", it's a matter of description. The period > isn't actually even 0xffff, that's just a pseudo-period, to reflect that > you have a choice of duty cycles of 0 to 0xffff. I (justifiably, I > think) didn't think putting this false value in the device tree was > accurate. Ok, I didn't investigate the driver to see what is truly set in HW. > >> rk3399-gru-kevin.dts). But e.g. sysfs could try to change the PWM period, >> there is no restriction to change the PWM period from sysfs, in the sysfs >> interface but the restriction is in PWM apply of the drive. The same things >> happens with these changes too. The user could introduce any PWM period via >> DT but the pwm apply function of the driver will return error. > > sysfs has no bearing on a device tree binding. Just because we have a > broken interface here doesn't mean we should change how we describe the > hardware. > Based on [1] and the comments I will drop the first 7 patches of this series. Thanks, Claudiu [1] https://www.kernel.org/doc/Documentation/devicetree/bindings/ABI.txt > Brian > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
