linux-kernel - Re: [PATCH v3] arm64: dts: qcom: sdm845-xiaomi-beryllium: Add DSI and panel bits

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Message-ID: <13bd5e9d-3f3b-0b97-aa48-9a7bc551ddf6@somainline.org>
Date:   Wed, 10 Feb 2021 19:55:37 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>
To:     Amit Pundir <amit.pundir@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Konrad Dybcio <konradybcio@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        John Stultz <john.stultz@...aro.org>,
        Sumit Semwal <sumit.semwal@...aro.org>
Cc:     linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        dt <devicetree@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>, phone-devel@...r.kernel.org
Subject: Re: [PATCH v3] arm64: dts: qcom: sdm845-xiaomi-beryllium: Add DSI and
 panel bits

Il 10/02/21 09:18, Amit Pundir ha scritto:
> From: Sumit Semwal <sumit.semwal@...aro.org>
> 
> Enabling the Display panel for beryllium requires DSI
> labibb regulators and panel dts nodes to be added.
> It is also required to keep some of the regulators as
> always-on.
> 
> Signed-off-by: Sumit Semwal <sumit.semwal@...aro.org>
> Signed-off-by: Amit Pundir <amit.pundir@...aro.org>
> ---

Hello!
Your patch looks good, however, I have a few concerns...

> v3: Addressed Konrad's concerns. Configured labibb regulators
>      explicitly based on downstream microvolt values. Display
>      comes up fine with default discharge-resistor-kohms and
>      soft-start-us properties, so didn't touch them.
>      Smoke tested on next-20210209.
> v2: Rebased to mainline (v5.11-rc6) and fixed build warnings.
> 
>   .../boot/dts/qcom/sdm845-xiaomi-beryllium.dts      | 64 ++++++++++++++++++++++
>   1 file changed, 64 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium.dts b/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium.dts
> index 86cbae63eaf7..5ac049a247e1 100644
> --- a/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium.dts
> +++ b/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium.dts
> @@ -157,6 +157,14 @@
>   			regulator-initial-mode = <RPMH_REGULATOR_MODE_HPM>;
>   		};
>   
> +		vreg_l14a_1p8: ldo14 {
> +			regulator-min-microvolt = <1800000>;
> +			regulator-max-microvolt = <1800000>;
> +			regulator-initial-mode = <RPMH_REGULATOR_MODE_HPM>;
> +			regulator-boot-on;
> +			regulator-always-on;
> +		};
> +
>   		vreg_l17a_1p3: ldo17 {
>   			regulator-min-microvolt = <1304000>;
>   			regulator-max-microvolt = <1304000>;
> @@ -191,6 +199,7 @@
>   			regulator-min-microvolt = <1200000>;
>   			regulator-max-microvolt = <1200000>;
>   			regulator-initial-mode = <RPMH_REGULATOR_MODE_HPM>;
> +			regulator-boot-on;
>   		};
>   	};
>   };
> @@ -200,6 +209,43 @@
>   	firmware-name = "qcom/sdm845/cdsp.mdt";
>   };
>   
> +&dsi0 {
> +	status = "okay";
> +	vdda-supply = <&vreg_l26a_1p2>;
> +
> +	#address-cells = <1>;
> +	#size-cells = <0>;
> +
> +	panel@0 {
> +		compatible = "tianma,fhd-video";
> +		reg = <0>;
> +		vddi0-supply = <&vreg_l14a_1p8>;
> +		vddpos-supply = <&lab>;
> +		vddneg-supply = <&ibb>;
> +
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +
> +		reset-gpios = <&tlmm 6 GPIO_ACTIVE_LOW>;
> +
> +		port {
> +			tianma_nt36672a_in_0: endpoint {
> +				remote-endpoint = <&dsi0_out>;
> +			};
> +		};
> +	};
> +};
> +
> +&dsi0_out {
> +	remote-endpoint = <&tianma_nt36672a_in_0>;
> +	data-lanes = <0 1 2 3>;
> +};
> +
> +&dsi0_phy {
> +	status = "okay";
> +	vdds-supply = <&vreg_l1a_0p875>;
> +};
> +
>   &gcc {
>   	protected-clocks = <GCC_QSPI_CORE_CLK>,
>   			   <GCC_QSPI_CORE_CLK_SRC>,
> @@ -215,6 +261,24 @@
>   	};
>   };
>   
> +&ibb {
> +	regulator-min-microvolt = <4600000>;
> +	regulator-max-microvolt = <6000000>;
> +};
> +

I think you want to also configure overvoltage and overcurrent 
protection values for both LAB and IBB, as these regulators may be a bit 
dangerous if used without.
Besides that, even if it wouldn't be that dangerous, since the 
protection features are present, it would be nice to configure them 
properly as in the rare event that something bad happens, you would be 
able to save the hardware (or at least have a chance to!).

> +&lab {
> +	regulator-min-microvolt = <4600000>;
> +	regulator-max-microvolt = <6000000>;
> +};
> +

Same here.

Yours,
-- Angelo

> +&mdss {
> +	status = "okay";
> +};
> +
> +&mdss_mdp {
> +	status = "okay";
> +};
> +
>   &mss_pil {
>   	status = "okay";
>   	firmware-name = "qcom/sdm845/mba.mbn", "qcom/sdm845/modem.mdt";
>