Message-ID: <3c07b9bd-1981-2945-9efe-80afb0195de8@linaro.org>
Date:   Sun, 29 Jan 2023 12:46:47 +0100
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Subject: Re: [PATCH 1/2] dt-bindings: display: bridge: Add NXP i.MX93 parallel
 display format configuration
Content-Language: en-US
To:     Liu Ying <victor.liu@nxp.com>, dri-devel@lists.freedesktop.org,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org
Cc:     andrzej.hajda@intel.com, neil.armstrong@linaro.org,
        robert.foss@linaro.org, Laurent.pinchart@ideasonboard.com,
        jonas@kwiboo.se, jernej.skrabec@gmail.com, airlied@gmail.com,
        daniel@ffwll.ch, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, shawnguo@kernel.org,
        s.hauer@pengutronix.de, kernel@pengutronix.de, festevam@gmail.com,
        linux-imx@nxp.com
References: <20230128034713.1530218-1-victor.liu@nxp.com>
 <20230128034713.1530218-2-victor.liu@nxp.com>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
In-Reply-To: <20230128034713.1530218-2-victor.liu@nxp.com>
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Precedence: bulk

On 28/01/2023 04:47, Liu Ying wrote:
> NXP i.MX93 mediamix blk-ctrl contains one DISPLAY_MUX register which
> configures parallel display format by using the "PARALLEL_DISP_FORMAT"
> field. Add device tree bindings for the display format configuration.
> 
> Signed-off-by: Liu Ying <victor.liu@nxp.com>
> ---
>  .../display/bridge/nxp,imx93-pdfc.yaml        | 78 +++++++++++++++++++
>  1 file changed, 78 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/bridge/nxp,imx93-pdfc.yaml
> 
> diff --git a/Documentation/devicetree/bindings/display/bridge/nxp,imx93-pdfc.yaml b/Documentation/devicetree/bindings/display/bridge/nxp,imx93-pdfc.yaml
> new file mode 100644
> index 000000000000..a84bfb46b01d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/bridge/nxp,imx93-pdfc.yaml
> @@ -0,0 +1,78 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/display/bridge/nxp,imx93-pdfc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: NXP i.MX93 Parallel Display Format Configuration
> +
> +maintainers:
> +  - Liu Ying <victor.liu@nxp.com>
> +
> +description: |
> +  The i.MX93 mediamix blk-ctrl contains one DISPLAY_MUX register which
> +  configures parallel display format by using the "PARALLEL_DISP_FORMAT"
> +  field.
> +
> +properties:
> +  compatible:
> +    const: nxp,imx93-pdfc


Based on description, I have doubts this is a separate bridge device.
Why this is not part of display driver/bindings?

We do not create usually devices for single registers, because they are
not a devices. Devices are a bit more complex - have some pin
inputs/outputs, not a register only. Of course there are exception, but
this one does not look like one.

> +
> +  reg:
> +    maxItems: 1

Your driver tells different story:

syscon_node_to_regmap(dev->of_node->parent);

(which also points to fact this is not a separate device)

Best regards,
Krzysztof