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@xxxxxxxxxxxxxxxxxx>:
> > 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@xxxxxxxxx>
> >> ---
> >> 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
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