Messages in this thread | | | Date | Mon, 15 Jan 2018 09:38:13 +0100 | From | Maxime Ripard <> | Subject | Re: [PATCH v1 4/4] ARM: dts: add pwm node for r40. |
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Hi,
On Sun, Jan 14, 2018 at 02:43:39PM +0800, Hao Zhang wrote: > 2018-01-11 20:47 GMT+08:00 Maxime Ripard <maxime.ripard@free-electrons.com>: > > On Thu, Jan 11, 2018 at 07:34:12PM +0800, hao_zhang wrote: > >> This patch add pwm node for r40. > >> > >> Signed-off-by: hao_zhang <hao5781286@gmail.com> > >> --- > >> arch/arm/boot/dts/sun8i-r40.dtsi | 13 +++++++++++++ > >> 1 file changed, 13 insertions(+) > >> > >> diff --git a/arch/arm/boot/dts/sun8i-r40.dtsi b/arch/arm/boot/dts/sun8i-r40.dtsi > >> index 173dcc1..84c963c 100644 > >> --- a/arch/arm/boot/dts/sun8i-r40.dtsi > >> +++ b/arch/arm/boot/dts/sun8i-r40.dtsi > >> @@ -295,6 +295,11 @@ > >> bias-pull-up; > >> }; > >> > >> + pwm_pins: pwm-pins { > >> + pins = "PB2", "PB3"; > >> + function = "pwm"; > >> + }; > >> + > > > > Is it the only combination of pins that is usable? > > > > If so, you can add the pinctrl-0 property directly in the pwm nodes. > > > > There are 8 channel pwm of R40/V40/T3, the pins that can be configed > to pwm are: PB2, PB3, PI20, PI21, PB20, PB21, PB9, PB10
And a single controller, or several of them?
> PB2, PB3 can be configed on bananapi-m2-ultra and on my T3 board, > but the other pins is not exist on the board or some pin is confilct > with other functions, so i just add PB2, PB3. but i think split it > is better, just like this : > > pwm0_pin: pwm0-pin { > pins = "PB2"; > function = "pwm"; > }; > > pwm1_pin: pwm1-pin { > pins = "PB3"; > function = "pwm"; > };
Yep, that would be better. If it's just a matter of channels, maybe we can even name them pwm-ch0-pin and pwm-ch1-pin? That would be more explicit.
> the node of pwm2~7 should also be added here?
If there's no users, no.
> On sun8i-r40-bananapi-m2-ultra.dts: > because of the special customize board, i think just add pinctrl-0 = <&pwm0_pin> > (PB3 I just use to test pwm channel 1)for bananapi-m2-ultra board is enough. > > &pwm { > pinctrl-names = "default"; > pinctrl-0 = <&pwm0_pin>; > status = "okay"; > };
It depends if that PWM is used as a PWM all the time (for example to drive a backlight for a panel tied to the board), or if it's exported through one of the generic pin headers, please leave it populated but disabled (with a comment that it is exported on one of the pin of the headers)
Thanks! Maxime
-- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com [unhandled content-type:application/pgp-signature] | |