linux-kernel - Re: pdm360ng and touchscreen set up

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Message-ID: <87r0c9i9qm.fsf@mail.lhotse>
Date: Thu, 04 Jul 2024 23:10:09 +1000
From: Michael Ellerman <mpe@...erman.id.au>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>, Anatolij Gustschin
 <agust@...x.de>
Cc: linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: pdm360ng and touchscreen set up

Dmitry Torokhov <dmitry.torokhov@...il.com> writes:
> Hi Anatolij, Michael,
>
> I hope you can shed some light for me: why does pdm360ng have very
> elaborate set up for the "pendown" GPIO of the touchscreen? Can we
> simply fix the DTS in arch/powerpc/boot/dts/pdm360ng.dts and specify
> correct pendown GPIO there, as well as correct interrupt trigger,
> and remove most of arch/powerpc/platforms/512x/pdm360ng.c ?

Sorry, I don't know anything about this platform.

It looks like it's some sort of embedded display device? It's pretty old
and hasn't seen much activity for ~10 years.

> Something like this:
>
> diff --git a/arch/powerpc/boot/dts/pdm360ng.dts b/arch/powerpc/boot/dts/pdm360ng.dts
> index 67c3b9db75d7..5651bd9d9db3 100644
> --- a/arch/powerpc/boot/dts/pdm360ng.dts
> +++ b/arch/powerpc/boot/dts/pdm360ng.dts
> @@ -176,11 +176,12 @@ psc@...00 {
>  
>  			/* ADS7845 touch screen controller */
>  			ts@0 {
> -				compatible = "ti,ads7846";
> +				compatible = "ti,ads7845";
>  				reg = <0x0>;
>  				spi-max-frequency = <3000000>;
>  				/* pen irq is GPIO25 */
> -				interrupts = <78 0x8>;
> +				interrupts = <78 IRQ_TYPE_LEVEL_LOW>;
> +				pendown-gpios = <&gpio 25 GPIO_ACTIVE_LOW>;
>  			};
>  		};
>  
>
>
> The reason I'm asking is that I want to remove support for platform
> data in ads7846 driver and pdm360ng is one of the last 3 users of it in
> the kernel.

I think go ahead with the change, and if anyone is still using this
device they can speak up if there's any problems.

cheers