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

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Date:   Tue, 22 Nov 2022 08:18:51 +0100
From:   David Jander <david@...tonic.nl>
To:     Fabio Estevam <festevam@...il.com>
Cc:     Quentin Schulz <foss+kernel@...il.net>,
        "Angus Ainslie (Purism)" <angus@...ea.ca>,
        Shawn Guo <shawnguo@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Heiko Stuebner <heiko@...ech.de>,
        Samuel Holland <samuel@...lland.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Bastien Nocera <hadess@...ess.net>,
        Chen-Yu Tsai <wens@...e.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Hans de Goede <hdegoede@...hat.com>,
        Andy Gross <agross@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        NXP Linux Team <linux-imx@....com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Quentin Schulz <quentin.schulz@...obroma-systems.com>,
        linux-kernel@...r.kernel.org, linux-rockchip@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-input@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
        devicetree@...r.kernel.org
Subject: Re: [PATCH RFC v2 5/7] arm64: dts: imx: fix touchscreen reset GPIO
 polarity

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

> [Adding Angus and David]

Thanks. This was apparently necessary ;-)

> On Mon, Nov 21, 2022 at 3:12 PM Quentin Schulz <foss+kernel@...il.net> wrote:
> >
> > From: Quentin Schulz <quentin.schulz@...obroma-systems.com>
> >
> > 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@...obroma-systems.com>
> > ---
> >  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.