linux-kernel - RE: [PATCH v3 1/2] dt-bindings: it6505: add properties to restrict output bandwidth

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Date:   Fri, 7 Oct 2022 03:18:23 +0000
From:   <allen.chen@....com.tw>
To:     <krzysztof.kozlowski@...aro.org>
CC:     <Jau-Chih.Tseng@....com.tw>, <Kenneth.Hung@....com.tw>,
        <Hermes.Wu@....com.tw>, <treapking@...omium.org>,
        <andrzej.hajda@...el.com>, <narmstrong@...libre.com>,
        <robert.foss@...aro.org>, <Laurent.pinchart@...asonboard.com>,
        <jonas@...boo.se>, <jernej.skrabec@...il.com>, <airlied@...ux.ie>,
        <daniel@...ll.ch>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>,
        <dri-devel@...ts.freedesktop.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3 1/2] dt-bindings: it6505: add properties to restrict
 output bandwidth

hi

-----Original Message-----
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org> 
Sent: Thursday, October 6, 2022 4:17 PM
To: Allen Chen (陳柏宇) <allen.chen@....com.tw>
Cc: Jau-Chih Tseng (曾昭智) <Jau-Chih.Tseng@....com.tw>; Kenneth Hung (洪家倫) <Kenneth.Hung@....com.tw>; Hermes Wu (吳佳宏) <Hermes.Wu@....com.tw>; Pin-yen Lin <treapking@...omium.org>; Andrzej Hajda <andrzej.hajda@...el.com>; Neil Armstrong <narmstrong@...libre.com>; Robert Foss <robert.foss@...aro.org>; Laurent Pinchart <Laurent.pinchart@...asonboard.com>; Jonas Karlman <jonas@...boo.se>; Jernej Skrabec <jernej.skrabec@...il.com>; David Airlie <airlied@...ux.ie>; Daniel Vetter <daniel@...ll.ch>; Rob Herring <robh+dt@...nel.org>; Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>; open list:DRM DRIVERS <dri-devel@...ts.freedesktop.org>; open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS <devicetree@...r.kernel.org>; open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/2] dt-bindings: it6505: add properties to restrict output bandwidth

On 06/10/2022 04:04, allen wrote:
> From: allen chen <allen.chen@....com.tw>
> 
> Add properties to restrict dp output data-lanes and clock.
> 
> Signed-off-by: Pin-Yen Lin <treapking@...omium.org>
> Signed-off-by: Allen Chen <allen.chen@....com.tw>
> ---
>  .../bindings/display/bridge/ite,it6505.yaml          | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git 
> a/Documentation/devicetree/bindings/display/bridge/ite,it6505.yaml 
> b/Documentation/devicetree/bindings/display/bridge/ite,it6505.yaml
> index 833d11b2303a..f5482a614d05 100644
> --- a/Documentation/devicetree/bindings/display/bridge/ite,it6505.yaml
> +++ b/Documentation/devicetree/bindings/display/bridge/ite,it6505.yaml
> @@ -52,6 +52,16 @@ properties:
>      maxItems: 1
>      description: extcon specifier for the Power Delivery
>  
> +  ite,dp-output-data-lane-count:
> +    description: restrict the dp output data-lanes with value of 1-4

Drop "with value of 1-4" because it is redundant, but instead explain what this property is about. "Restrict output" is not yet enough.
Restrict the number? Or choose specific lanes? Why it cannot be data-lanes from video-interfaces?

==> DP output bandwidth depends on data-lane-count, so the number of output data-lane-count will restrict output bandwidth.
In this dt-binding we don't have output endpoint, so use another property name to configure.
If need to use data-lanes, where can we put in this dt-binding?

> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    enum: [ 1, 2, 4 ]
> +
> +  ite,dp-output-max-pixel-clock-mhz:

Test your patches before sending.

Best regards,
Krzysztof