linux-kernel - Re: [PATCH] dt-bindings: input: touchscreen: edt-ft5x06: change reg property

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Date:   Thu, 28 May 2020 16:01:36 -0600
From:   Rob Herring <robh@...nel.org>
To:     Heiko Stübner <heiko@...ech.de>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Johan Jonker <jbx6244@...il.com>, linux-input@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dt-bindings: input: touchscreen: edt-ft5x06: change reg
 property

On Wed, May 20, 2020 at 08:41:59PM +0200, Heiko Stübner wrote:
> Hi Dmitry,
> 
> Am Mittwoch, 20. Mai 2020, 19:13:24 CEST schrieb Dmitry Torokhov:
> > Hi Johan,
> > 
> > On Wed, May 20, 2020 at 09:33:27AM +0200, Johan Jonker wrote:
> > > A test with the command below gives this error:
> > > 
> > > arch/arm/boot/dts/rk3188-bqedison2qc.dt.yaml:
> > > touchscreen@3e: reg:0:0: 56 was expected
> > > 
> > > The touchscreen chip on 'rk3188-bqedison2qc' and other BQ models
> > > was shipped with different addresses then the binding currently allows.
> > > Change the reg property that any address will pass.
> > > 
> > > make ARCH=arm dtbs_check
> > > DT_SCHEMA_FILES=Documentation/devicetree/bindings/input/touchscreen/
> > > edt-ft5x06.yaml
> > > 
> > > Signed-off-by: Johan Jonker <jbx6244@...il.com>
> > > ---
> > >  Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.yaml | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.yaml b/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.yaml
> > > index 383d64a91..baa8e8f7e 100644
> > > --- a/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.yaml
> > > +++ b/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.yaml
> > > @@ -42,7 +42,7 @@ properties:
> > >        - focaltech,ft6236
> > >  
> > >    reg:
> > > -    const: 0x38
> > > +    maxItems: 1
> > 
> > Should we have a list of valid addresses instead of allowing any
> > address? Controllers usually have only a couple of addresses that they
> > support.
> 
> from what I've read, the fdt touchscreen controllers are just a generic
> cpu with device-specific (or better panel-specific) firmware, which seems
> to include the address as well - so it looks to be variable.
> 
> But of course that is only 2nd hand knowledge for me ;-)
> 
> 
> But also, the i2c address is something you cannot really mess up,
> either it is correct and your touchscreen works, or it isn't and and
> adding entries to this list every time a new address variant pops up
> feels clumsy.

Is that an Ack?

I'm fine either way. It's really only useful if there's a single 
address because with a list it could still be wrong just as any other 
data like an interrupt number could be wrong.

Rob