Re: [PATCH] arm64: dts: meson: Enable active coling using gpio-fan on Odroid N2/N2+

[neil . armstrong]

On 21/10/2022 07:07, Anand Moon wrote:
> Hi Martin / Neil,
>
> On Thu, 20 Oct 2022 at 02:10, Martin Blumenstingl
> <martin.blumenstingl@xxxxxxxxxxxxxx> wrote:
> > Hi Anand,
> >
> > On Wed, Oct 19, 2022 at 7:17 PM Anand Moon <linux.amoon@xxxxxxxxx> wrote:
> > [...]
> > > > > +&pwm_AO_ab {
> > > >
> > > > &pwm_AO_cd not _ab
> > > No it has a conflict with CPU_B (vddcpu_b) PWM
> > Uh, you're right. That's probably why the Hardkernel team uses a
> > software based PWM implementation: [0]
> > In hindsight they should have used a different pad either for VDDCPU_B
> > or the fan.
> >
> > I think the most pragmatic approach (since the "GPIO PWM" driver is
> > not upstream and I don't know if something like that would be accepted
> > upstream) is to use a GPIO based fan as you did in your initial patch.
> > Not sure what others think though.
>
> When I use gpio-fan  I get the following output with gpioinfo
> Feature it woks as expected.
>
> $ .sudo gpioinfo
> ....
> gpiochip1 - 15 lines:
>          line   0:      unnamed       unused   input  active-high
>          line   1:      unnamed       unused   input  active-high
>          line   2:      unnamed     "enable"  output  active-high [used]
>          line   3:      unnamed       unused   input  active-high
>          line   4:      unnamed       unused  output  active-high
>          line   5:      unnamed       unused   input  active-high
>          line   6:      unnamed       unused   input  active-high
>          line   7:      unnamed       unused   input  active-high
>          line   8:      unnamed "regulator-tflash_vdd" output active-high [used]
>          line   9:      unnamed      "TF_IO"  output  active-high [used]
>          line  10:      unnamed   "gpio-fan"  output  active-high [used]
>          line  11:      unnamed    "n2:blue"  output  active-high [used]
>          line  12:      unnamed       unused   input  active-high
>          line  13:      unnamed       unused   input  active-high
>          line  14:      unnamed       unused   input  active-high
>
> When I am using pwm-fan using *pwm_ao_d_10_pins* pin is not getting
> registered below hence it is not working on my end.

It's expected because it's not used as a GPIO but another function, you should look
in the pinctrl debugfs files to see it.

> $ .sudo gpioinfo
> ....
> gpiochip1 - 15 lines:
>          line   0:      unnamed       unused   input  active-high
>          line   1:      unnamed       unused   input  active-high
>          line   2:      unnamed     "enable"  output  active-high [used]
>          line   3:      unnamed       unused   input  active-high
>          line   4:      unnamed       unused  output  active-high
>          line   5:      unnamed       unused   input  active-high
>          line   6:      unnamed       unused   input  active-high
>          line   7:      unnamed       unused   input  active-high
>          line   8:      unnamed "regulator-tflash_vdd" output active-high [used]
>          line   9:      unnamed      "TF_IO"  output  active-high [used]
>          line  10:      unnamed       unused  output  active-high
>          line  11:      unnamed    "n2:blue"  output  active-high [used]
>          line  12:      unnamed       unused   input  active-high
>          line  13:      unnamed       unused   input  active-high
>          line  14:      unnamed       unused   input  active-high
>
> Thanks
> -Anand
>
>
>
>
> > Best regards,
> > Martin
> >
> >
> > [0] https://github.com/hardkernel/linux/blob/c109dec94e7e819554830acfac4b6ed96e230179/arch/arm64/boot/dts/amlogic/meson64_odroidn2.dtsi#L356-L359