On Mon, Apr 12, 2021 at 06:27:23PM +0200, Uwe Kleine-König wrote: > On Mon, Apr 12, 2021 at 03:27:41PM +0200, Clemens Gruber wrote: > > Add the flag and corresponding documentation for PWM_USAGE_POWER. > > My concern here in the previous round was that PWM_USAGE_POWER isn't a > name that intuitively suggests its semantic. Do you disagree?
No. It is more abstract and requires documentation. But I also didn't want to waste too much time on discussing names, so I used Thierry's suggestion. I guess we need his input on this subject. I can live both with PWM_ALLOW_PHASE_SHIFTING and PWM_USAGE_POWER, as long as it is documented well enough. > > > Cc: Rob Herring <robh...@kernel.org> > > Signed-off-by: Clemens Gruber <clemens.gru...@pqgruber.com> > > --- > > Documentation/devicetree/bindings/pwm/pwm.txt | 3 +++ > > include/dt-bindings/pwm/pwm.h | 1 + > > 2 files changed, 4 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/pwm/pwm.txt > > b/Documentation/devicetree/bindings/pwm/pwm.txt > > index 084886bd721e..fe3a28f887c0 100644 > > --- a/Documentation/devicetree/bindings/pwm/pwm.txt > > +++ b/Documentation/devicetree/bindings/pwm/pwm.txt > > @@ -46,6 +46,9 @@ 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_USAGE_POWER: Only care about the power output of the signal. This > > + allows drivers (if supported) to optimize the signals, for example to > > + improve EMI and reduce current spikes. > > IMHO there are too many open questions about which freedom this gives to > the lowlevel driver. If the consumer requests .duty_cycle = 25ns + > .period = 100ns, can the driver provide .duty_cycle = 25s + .period = > 100s which nominally has the same power output? Let's not introduce more > ambiguity than there already is. > > This is a NAck. > > Best regards > Uwe > > -- > Pengutronix e.K. | Uwe Kleine-König | > Industrial Linux Solutions | https://www.pengutronix.de/ |
