linux-kernel - Re: [PATCH 1/2] dt-bindings: display: panel: Add Visionox R66451 AMOLED DSI panel bindings

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Date:   Fri, 26 May 2023 09:42:33 +0200
From:   Neil Armstrong <neil.armstrong@...aro.org>
To:     Marijn Suijten <marijn.suijten@...ainline.org>
Cc:     Jessica Zhang <quic_jesszhan@...cinc.com>,
        Sam Ravnborg <sam@...nborg.org>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        devicetree@...r.kernel.org,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: display: panel: Add Visionox R66451
 AMOLED DSI panel bindings

On 22/05/2023 16:51, Marijn Suijten wrote:
> On 2023-05-22 11:05:38, Neil Armstrong wrote:
>> On 21/05/2023 12:30, Marijn Suijten wrote:
>>> On 2023-05-16 13:20:30, Jessica Zhang wrote:
>>>> Document the 1080x2340 Visionox R66451 AMOLED DSI panel bindings
>>>>
>>>> Signed-off-by: Jessica Zhang <quic_jesszhan@...cinc.com>
>>>> ---
>>>>    .../bindings/display/panel/visionox,r66451.yaml    | 59 ++++++++++++++++++++++
>>>>    1 file changed, 59 insertions(+)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/display/panel/visionox,r66451.yaml b/Documentation/devicetree/bindings/display/panel/visionox,r66451.yaml
>>>> new file mode 100644
>>>> index 000000000000..6ba323683921
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/display/panel/visionox,r66451.yaml
>>>> @@ -0,0 +1,59 @@
>>>> +# SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause
>>>> +%YAML 1.2
>>>> +---
>>>> +$id: http://devicetree.org/schemas/display/panel/visionox,r66451.yaml#
>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>> +
>>>> +title: Visionox R66451 AMOLED DSI Panel
>>>> +
>>>> +maintainers:
>>>> +  - Jessica Zhang <quic_jesszhan@...cinc.com>
>>>> +
>>>> +allOf:
>>>> +  - $ref: panel-common.yaml#
>>>> +
>>>> +properties:
>>>> +  compatible:
>>>> +    const: visionox,r66451
>>>> +
>>>> +  reg:
>>>> +    maxItems: 1
>>>> +    description: DSI virtual channel
>>>> +
>>>> +  vddio-supply: true
>>>> +  vdd-supply: true
>>>> +  port: true
>>>> +  reset-gpios: true
>>>
>>> Normally for cmd-mode panels there is also a `disp-te` pin which is
>>> optionally registered in dsi_host.c as GPIOD_IN, but on **ALL** my Sony
>>> phones this breaks vsync (as in: mdp5 stops receiving the interrupt, but
>>> we can see disp-te in /proc/interrupts then).
>>
>> Describing it as a gpio is wrong, it should be described as a pinctrl state instead.
> 
> We defined both in our DTS, what weirdness does it cause when then
> requested using GPIOD_IN?  It'd still be beneficial to see the vsync
> interrupt raise in /proc/interrupts (but it's just a waste of CPU cycles
> OTOH, this is all handled in the MDP hardware after all, so it's not
> something I'd like to enable by default).

Sure, but it's a sw hack, the pin has a TE function which directly goes to
the DSI logic, claiming it as a GPIO will set it as GPIO function.

On some platforms, PINMUX is only on output and input is always directed
to all HW blocks, seems it's not the case here !

> 
> Anyway, this is what we ended up doing to "fix" the bug (only bias the
> pin via pinctrl, omit the disp-te DTS property).  Thanks for confirming!
> 
> - Marijn
> 
>>
>> Neil
> 
> <snip>