linux-kernel - Re: [PATCH v2 3/4] arm64: dts: qcom: Disable MDSS by default for 8916/8016 devices

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Message-ID: <YBVC2KfT4pLJ5/XX@gerhold.net>
Date:   Sat, 30 Jan 2021 12:28:24 +0100
From:   Stephan Gerhold <stephan@...hold.net>
To:     Vincent Knecht <vincent.knecht@...loo.org>
Cc:     phone-devel@...r.kernel.org, ~postmarketos/upstreaming@...ts.sr.ht,
        Rob Herring <robh+dt@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Sam Ravnborg <sam@...nborg.org>, Arnd Bergmann <arnd@...db.de>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Daniel Palmer <daniel@...f.com>,
        Oleksij Rempel <linux@...pel-privat.de>,
        Max Merchel <Max.Merchel@...group.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        allen <allen.chen@....com.tw>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v2 3/4] arm64: dts: qcom: Disable MDSS by default for
 8916/8016 devices

On Sat, Jan 30, 2021 at 11:57:12AM +0100, Vincent Knecht wrote:
> Disable MDSS (Mobile Display Subsystem) by default in msm8916.dtsi
> and only explicitly enable it in devices' DT which actually use it.
> 
> This leads to faster boot and cleaner logs for other devices,
> which also won't have to explicitly disable MDSS to use framebuffer.
> 
> Signed-off-by: Vincent Knecht <vincent.knecht@...loo.org>

Thanks for the patch! I think this is a good thing because normally most
things are disabled by default in msm8916.dtsi (e.g. eMMC, SD card,
WCNSS, ....). Also, there are actually some devices that don't have a
display (e.g. the 4IoT board [1]). Having to disable it specifically is
kind of weird. So:

Reviewed-by: Stephan Gerhold <stephan@...hold.net>

[1]: https://www.96boards.org/product/4iot/

> ---
>  arch/arm64/boot/dts/qcom/apq8016-sbc.dtsi                  | 4 ++++
>  arch/arm64/boot/dts/qcom/msm8916-samsung-a2015-common.dtsi | 4 ++++
>  arch/arm64/boot/dts/qcom/msm8916.dtsi                      | 1 +
>  3 files changed, 9 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/apq8016-sbc.dtsi b/arch/arm64/boot/dts/qcom/apq8016-sbc.dtsi
> index 3a9538e1ec97..6aef0c2e4f0a 100644
> --- a/arch/arm64/boot/dts/qcom/apq8016-sbc.dtsi
> +++ b/arch/arm64/boot/dts/qcom/apq8016-sbc.dtsi
> @@ -301,6 +301,10 @@ &lpass {
>  	status = "okay";
>  };
>  
> +&mdss {
> +	status = "okay";
> +};
> +
>  &pm8916_resin {
>  	status = "okay";
>  	linux,code = <KEY_VOLUMEDOWN>;
> diff --git a/arch/arm64/boot/dts/qcom/msm8916-samsung-a2015-common.dtsi b/arch/arm64/boot/dts/qcom/msm8916-samsung-a2015-common.dtsi
> index f1af798abd74..230ba3ce3277 100644
> --- a/arch/arm64/boot/dts/qcom/msm8916-samsung-a2015-common.dtsi
> +++ b/arch/arm64/boot/dts/qcom/msm8916-samsung-a2015-common.dtsi
> @@ -132,6 +132,10 @@ &dsi0 {
>  	pinctrl-1 = <&mdss_sleep>;
>  };
>  
> +&mdss {
> +	status = "okay";
> +};
> +
>  &pm8916_resin {
>  	status = "okay";
>  	linux,code = <KEY_VOLUMEDOWN>;
> diff --git a/arch/arm64/boot/dts/qcom/msm8916.dtsi b/arch/arm64/boot/dts/qcom/msm8916.dtsi
> index 402e891a84ab..8f9a651d3827 100644
> --- a/arch/arm64/boot/dts/qcom/msm8916.dtsi
> +++ b/arch/arm64/boot/dts/qcom/msm8916.dtsi
> @@ -913,6 +913,7 @@ tcsr: syscon@...7000 {
>  		};
>  
>  		mdss: mdss@...0000 {
> +			status = "disabled";
>  			compatible = "qcom,mdss";
>  			reg = <0x01a00000 0x1000>,
>  			      <0x01ac8000 0x3000>;
> -- 
> 2.29.2
> 
> 
>