Hello Thierry, On Tue, Mar 17, 2020 at 06:43:44PM +0100, Thierry Reding wrote: > On Tue, Mar 17, 2020 at 02:32:26PM +0200, Oleksandr Suvorov wrote: > > Add the description of PWM_POLARITY_NORMAL flag. > > > > Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@xxxxxxxxxxx> > > --- > > > > Documentation/devicetree/bindings/pwm/pwm.txt | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/Documentation/devicetree/bindings/pwm/pwm.txt b/Documentation/devicetree/bindings/pwm/pwm.txt > > index 084886bd721e..440c6b9a6a4e 100644 > > --- a/Documentation/devicetree/bindings/pwm/pwm.txt > > +++ b/Documentation/devicetree/bindings/pwm/pwm.txt > > @@ -46,6 +46,7 @@ period in nanoseconds. > > Optionally, the pwm-specifier can encode a number of flags (defined in > > <dt-bindings/pwm/pwm.h>) in a third cell: > > - PWM_POLARITY_INVERTED: invert the PWM signal polarity > > +- PWM_POLARITY_NORMAL: don't invert the PWM signal polarity > > This doesn't make sense. PWM_POLARITY_NORMAL is not part of the DT ABI. "is not part of the DT ABI" is hardly a good reason. If it's sensible to be used, it is sensible to define it. (And as far as I understand it, the term PWM_POLARITY_INVERTED isn't part of the DT ABI either. Only the value 1 has a meaning (for some PWM controlers).) > The third cell of the specifier is a bitmask of flags. > > PWM_POLARITY_NORMAL is an enumeration value that evaluates to 0, so it > makes absolutely no sense as a flag. Using 0 or PWM_POLARITY_NORMAL doesn't have an effect on the compiled device tree, that's true. But having the term PWM_POLARITY_NORMAL (in contrast to a plain 0) in a dts file is useful in my eyes for human readers. > PWM signals are considered to be "normal" by default, so no flag is > necessary to specify that. GPIOs are considered to be active high by default, still there is GPIO_ACTIVE_HIGH (which also evaluates to 0). Also there is IRQ_TYPE_NONE. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ |
