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

From: <allen.chen@ite.com.tw>
To: <krzysztof.kozlowski@linaro.org>
Cc: devicetree@vger.kernel.org, Kenneth.Hung@ite.com.tw,
	jernej.skrabec@gmail.com, krzysztof.kozlowski+dt@linaro.org,
	narmstrong@baylibre.com, airlied@linux.ie,
	dri-devel@lists.freedesktop.org, Jau-Chih.Tseng@ite.com.tw,
	linux-kernel@vger.kernel.org, robert.foss@linaro.org,
	treapking@chromium.org, Hermes.Wu@ite.com.tw, robh+dt@kernel.org,
	Laurent.pinchart@ideasonboard.com, andrzej.hajda@intel.com,
	jonas@kwiboo.se
Subject: RE: [PATCH v3 1/2] dt-bindings: it6505: add properties to restrict output bandwidth
Date: Fri, 7 Oct 2022 03:18:23 +0000	[thread overview]
Message-ID: <7acf5664832f43fbaa684c19415894c7@ite.com.tw> (raw)
In-Reply-To: <94c660bc-b7eb-1aea-8ae2-0ee7993091fd@linaro.org>

hi

-----Original Message-----
From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> 
Sent: Thursday, October 6, 2022 4:17 PM
To: Allen Chen (陳柏宇) <allen.chen@ite.com.tw>
Cc: Jau-Chih Tseng (曾昭智) <Jau-Chih.Tseng@ite.com.tw>; Kenneth Hung (洪家倫) <Kenneth.Hung@ite.com.tw>; Hermes Wu (吳佳宏) <Hermes.Wu@ite.com.tw>; Pin-yen Lin <treapking@chromium.org>; Andrzej Hajda <andrzej.hajda@intel.com>; Neil Armstrong <narmstrong@baylibre.com>; Robert Foss <robert.foss@linaro.org>; Laurent Pinchart <Laurent.pinchart@ideasonboard.com>; Jonas Karlman <jonas@kwiboo.se>; Jernej Skrabec <jernej.skrabec@gmail.com>; David Airlie <airlied@linux.ie>; Daniel Vetter <daniel@ffwll.ch>; Rob Herring <robh+dt@kernel.org>; Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>; open list:DRM DRIVERS <dri-devel@lists.freedesktop.org>; open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS <devicetree@vger.kernel.org>; open list <linux-kernel@vger.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@ite.com.tw>
> 
> Add properties to restrict dp output data-lanes and clock.
> 
> Signed-off-by: Pin-Yen Lin <treapking@chromium.org>
> Signed-off-by: Allen Chen <allen.chen@ite.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