Re: [PATCH RFC v2 5/7] arm64: dts: imx: fix touchscreen reset GPIO polarity

[David Jander]

On Mon, 21 Nov 2022 15:18:32 -0300
Fabio Estevam <festevam@xxxxxxxxx> wrote:

> [Adding Angus and David]

Thanks. This was apparently necessary ;-)

> On Mon, Nov 21, 2022 at 3:12 PM Quentin Schulz <foss+kernel@xxxxxxxxx> wrote:
> >
> > From: Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxxxxx>
> >
> > The reset line is active low for the Goodix touchscreen controller so
> > let's fix the polarity in the Device Tree node.
> >
> > Signed-off-by: Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxxxxx>
> > ---
> >  arch/arm64/boot/dts/freescale/imx8mm-prt8mm.dts         | 2 +-
> >  arch/arm64/boot/dts/freescale/imx8mq-librem5-devkit.dts | 2 +-
> >  2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/boot/dts/freescale/imx8mm-prt8mm.dts b/arch/arm64/boot/dts/freescale/imx8mm-prt8mm.dts
> > index 9fbbbb556c0b3..df7e5ae9698e1 100644
> > --- a/arch/arm64/boot/dts/freescale/imx8mm-prt8mm.dts
> > +++ b/arch/arm64/boot/dts/freescale/imx8mm-prt8mm.dts
> > @@ -107,7 +107,7 @@ touchscreeen@5d {
> >                 interrupt-parent = <&gpio1>;
> >                 interrupts = <8 IRQ_TYPE_NONE>;
> >                 irq-gpios = <&gpio1 8 GPIO_ACTIVE_HIGH>;
> > -               reset-gpios = <&gpio1 9 GPIO_ACTIVE_HIGH>;
> > +               reset-gpios = <&gpio1 9 GPIO_ACTIVE_LOW>;

NACK!

The PRT8MM has an inverter in the reset line. The reason for that is that the
reset line needs to be inactive when the driving side is unpowered.
The DT was correct, this change will break it.

> >         };
> >
> >         temp-sense@70 {
> > diff --git a/arch/arm64/boot/dts/freescale/imx8mq-librem5-devkit.dts b/arch/arm64/boot/dts/freescale/imx8mq-librem5-devkit.dts
> > index 6445c6b90b5bb..b038300812b1e 100644
> > --- a/arch/arm64/boot/dts/freescale/imx8mq-librem5-devkit.dts
> > +++ b/arch/arm64/boot/dts/freescale/imx8mq-librem5-devkit.dts
> > @@ -542,7 +542,7 @@ touchscreen@5d {
> >                 pinctrl-0 = <&pinctrl_ts>;
> >                 interrupt-parent = <&gpio3>;
> >                 interrupts = <0 IRQ_TYPE_LEVEL_LOW>;
> > -               reset-gpios = <&gpio1 5 GPIO_ACTIVE_HIGH>;
> > +               reset-gpios = <&gpio1 5 GPIO_ACTIVE_LOW>;
> >                 irq-gpios = <&gpio3 0 GPIO_ACTIVE_HIGH>;
> >                 touchscreen-size-x = <720>;
> >                 touchscreen-size-y = <1440>;
> >
> > --
> > b4 0.10.1  

Best regards,

-- 
David Jander
Protonic Holland.