linux-kernel - Re: [PATCH v2] dt-bindings: input: Goodix SPI HID Touchscreen

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Message-ID: <CAD=FV=UQr_6L_UhdCSr3cbxfGO2aEEYgTEpBh+gseYeapr-5iA@mail.gmail.com>
Date: Thu, 7 Nov 2024 13:54:33 -0800
From: Doug Anderson <dianders@...omium.org>
To: Charles Wang <charles.goodix@...il.com>
Cc: krzk@...nel.org, hbarnor@...omium.org, conor.dooley@...rochip.com, 
	dmitry.torokhov@...il.com, jikos@...nel.org, bentiss@...nel.org, 
	linux-input@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] dt-bindings: input: Goodix SPI HID Touchscreen

Hi,

On Wed, Nov 6, 2024 at 7:23 PM Charles Wang <charles.goodix@...il.com> wrote:
>
> The Goodix GT7986U touch controller report touch data according to the
> HID protocol through the SPI bus. However, it is incompatible with
> Microsoft's HID-over-SPI protocol.

I think it was requested that both the yaml file and the commit
message mention why there are two different yaml file that both talk
about "gt7986u". In the commit message I think it would be valuable to
point to the previous discussion. AKA, maybe say:

NOTE: these bindings are distinct from the bindings used with the
GT7986U when the chip is running I2C firmware. For some background,
see discussion on the mailing lists in the thread:

https://lore.kernel.org/r/20241018020815.3098263-2-charles.goodix@gmail.com

> Signed-off-by: Charles Wang <charles.goodix@...il.com>
> ---
> Changes in v2:
> - Change compatible to 'goodix,gt7986u-spifw'.
> - Remove 'goodix,hid-report-addr' property.

Probably this should be a two-patch series now. The first is this
bindings file and the second changes the firmware (which never got
reverted) to default to a hid-report-addr of 1.

> - Change additionalProperties to unevaluatedProperties.
> - v1: https://lore.kernel.org/all/20241025114642.40793-2-charles.goodix@gmail.com/
> ---
>  .../bindings/input/goodix,gt7986u.yaml        | 66 +++++++++++++++++++
>  1 file changed, 66 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/goodix,gt7986u.yaml

The name of the file needs to match the primary compatible, so it
should include the "-spifw" part.

> diff --git a/Documentation/devicetree/bindings/input/goodix,gt7986u.yaml b/Documentation/devicetree/bindings/input/goodix,gt7986u.yaml
> new file mode 100644
> index 000000000..b7afa21fb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/goodix,gt7986u.yaml
> @@ -0,0 +1,66 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/input/goodix,gt7986u.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Goodix GT7986U SPI HID Touchscreen
> +
> +maintainers:
> +  - Charles Wang <charles.goodix@...il.com>
> +
> +description: Supports the Goodix GT7986U touchscreen.
> +  This touch controller reports data packaged according to the HID protocol
> +  over the SPI bus, but it is incompatible with Microsoft's HID-over-SPI protocol.

I probably would have put the note about the compatible here instead
of below. Something like:

NOTE: these bindings are distinct from the bindings used with the
GT7986U when the chip is running I2C firmware. This is because there's
not a single device that talks over both I2C and SPI but rather
distinct touchscreens that happen to be built with the same ASIC but
that are distinct products running distinct firmware.

> +allOf:
> +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
> +
> +properties:
> +  compatible:
> +    description:
> +      Add the 'spifw' suffix to distinguish it from the general GT7986U I2C-HID
> +      touchscreen, as it runs a substantially different firmware than GT7986U
> +      I2C-HID touchscreens.

As per above, I'd remove the "description" here. It's not common for a
compatible to have a "description".

> +    enum:
> +      - goodix,gt7986u-spifw
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  reset-gpios:
> +    maxItems: 1
> +
> +  spi-max-frequency: true
> +
> +unevaluatedProperties: false

I believe "unevaluatedProperties" is supposed to be moved down below
"required" according to previous comments on your patches.