linux-kernel - Re: [PATCH v1 1/2] dt-bindings: display: panel: raspberrypi: Add compatible property for waveshare 7inch touchscreen panel

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Message-ID: <20231206-isolating-smoked-b490952029d0@spud>
Date:   Wed, 6 Dec 2023 15:40:21 +0000
From:   Conor Dooley <conor@...nel.org>
To:     Shengyang Chen <shengyang.chen@...rfivetech.com>
Cc:     devicetree@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        neil.armstrong@...aro.org, quic_jesszhan@...cinc.com,
        sam@...nborg.org, airlied@...il.com, daniel@...ll.ch,
        maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
        tzimmermann@...e.de, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        florian.fainelli@...adcom.com,
        bcm-kernel-feedback-list@...adcom.com, eric@...olt.net,
        thierry.reding@...il.com, changhuang.liang@...rfivetech.com,
        keith.zhao@...rfivetech.com, jack.zhu@...rfivetech.com,
        linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/2] dt-bindings: display: panel: raspberrypi: Add
 compatible property for waveshare 7inch touchscreen panel

On Wed, Dec 06, 2023 at 05:43:48PM +0800, Shengyang Chen wrote:
> Hi, Conor
> 
> On 2023/11/24 20:31, Conor Dooley wrote:
> > On Fri, Nov 24, 2023 at 06:44:50PM +0800, Shengyang Chen wrote:
> >> The waveshare 7inch touchscreen panel is a kind of raspberrypi pi
> >> panel
> > 
> > Can you be more specific about what "is a kind of rpi panel" means?
> > Are they using identical chips as controllers or something like that?
> > 
> 
> Wareshare panel has same i2c slave address and registers address with 
> the original raspberry pi panel. They both use Atmel firmware and they
> got same reg id. It can be operated by using the driver of raspberry pi driver
> after some change of the code. So I suppose it may be a kind of raspberry pi panel 
> and discribe it in this way. It's my own judgement. Sorry about that.
> Maybe just like Dave said, It cloned the behaviour of the raspberri pi panel.
> I will change the discribtion in next version to not make other confused.
> 
> By the way, we will try Stefan's method before next version. 
> The method we used in this patch may be abandoned if Stefan's method is verified in our platform.
> At that time yaml may also be changed to fit new method.

I don't know what Stefan's approach is, but I do not think that a
bindings patch should be dropped. The waveshare might be a clone, but it
is a distinct device. If the same driver can control both, then the
compatible setups that should be permitted are:
compatible = "raspberrypi,7inch-touchscreen-panel";
and
compatible = "waveshare,7inch-touchscreen-panel", "raspberrypi,7inch-touchscreen-panel";

Cheers,
Conor.

> >> and it can be drived by panel-raspberrypi-touchscreen.c.
> >> Add compatible property for it.
> >> 
> >> Signed-off-by: Keith Zhao <keith.zhao@...rfivetech.com>
> >> Signed-off-by: Shengyang Chen <shengyang.chen@...rfivetech.com>
> >> ---
> >>  .../bindings/display/panel/raspberrypi,7inch-touchscreen.yaml | 4 +++-
> >>  1 file changed, 3 insertions(+), 1 deletion(-)
> >> 
> >> diff --git a/Documentation/devicetree/bindings/display/panel/raspberrypi,7inch-touchscreen.yaml b/Documentation/devicetree/bindings/display/panel/raspberrypi,7inch-touchscreen.yaml
> >> index 22a083f7bc8e..e4e6cb4d4e5b 100644
> >> --- a/Documentation/devicetree/bindings/display/panel/raspberrypi,7inch-touchscreen.yaml
> >> +++ b/Documentation/devicetree/bindings/display/panel/raspberrypi,7inch-touchscreen.yaml
> >> @@ -22,7 +22,9 @@ description: |+
> >>  
> >>  properties:
> >>    compatible:
> >> -    const: raspberrypi,7inch-touchscreen-panel
> >> +    enum:
> >> +      - raspberrypi,7inch-touchscreen-panel
> >> +      - waveshare,7inch-touchscreen-panel
> >>  
> >>    reg:
> >>      const: 0x45
> >> -- 
> >> 2.17.1
> >> 
> 
> 
> thanks.
> 
> Best Regards,
> Shengyang
> 

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