linux-kernel - Re: [PATCH v2] arm64: dts: qcom: sc7180: Add Display Port dt node

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Date:   Thu, 18 Jun 2020 18:12:47 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Tanmay Shah <tanmay@...eaurora.org>, agross@...nel.org
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, seanpaul@...omium.org,
        robdclark@...il.com, dianders@...omium.org,
        aravindh@...eaurora.org, abhinavk@...eaurora.org,
        bjorn.andersson@...aro.org, Tanmay Shah <tanmay@...eaurora.org>
Subject: Re: [PATCH v2] arm64: dts: qcom: sc7180: Add Display Port dt node

Quoting Tanmay Shah (2020-06-18 16:21:13)
> Enable DP driver for sc7180.

Add DP device node on sc7180? This isn't a driver.

> 
> This change depends-on following series:
> https://patchwork.freedesktop.org/series/78583/
> and https://patchwork.freedesktop.org/patch/351990/
> 
> Changes in v2:
> 
> - Add assigned-clocks and assigned-clock-parents
> - Remove cell-index and pixel_rcg
> - Change compatible to qcom,sc7180-dp
> 
> Signed-off-by: Tanmay Shah <tanmay@...eaurora.org>
> ---
>  arch/arm64/boot/dts/qcom/sc7180.dtsi | 57 ++++++++++++++++++++++++++--
>  1 file changed, 53 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sc7180.dtsi b/arch/arm64/boot/dts/qcom/sc7180.dtsi
> index 916401f7e87c..26fe623e3b0f 100644
> --- a/arch/arm64/boot/dts/qcom/sc7180.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sc7180.dtsi
> @@ -2216,10 +2216,19 @@ ports {
>                                         #address-cells = <1>;
>                                         #size-cells = <0>;
>  
> +                                       port@1 {
> +                                               reg = <1>;
> +                                               dpu_intf1_out: endpoint {
> +                                                       remote-endpoint =
> +                                                                <&dsi0_in>;
> +                                               };
> +                                       };
> +
>                                         port@0 {
>                                                 reg = <0>;
> -                                               dpu_intf1_out: endpoint {
> -                                                       remote-endpoint = <&dsi0_in>;
> +                                               dpu_intf0_out: endpoint {
> +                                                       remote-endpoint =
> +                                                                <&dp_in>;
>                                                 };
>                                         };
>                                 };

I thought this wasn't supposed to change? At least according to the
binding it shouldn't be needed.

> @@ -2293,6 +2302,46 @@ dsi_phy: dsi-phy@...4400 {
>                         };
>                 };
>  
> +               msm_dp: displayport-controller@...0000{
> +                       status = "ok";

Please use status = "disabled";

> +                       compatible = "qcom,sc7180-dp";
> +
> +                       reg = <0 0xae90000 0 0x1400>;
> +                       reg-names = "dp_controller";
> +
> +                       interrupt-parent = <&mdss>;

Any reason why this isn't under the mdss node like the other display
device nodes?

> +                       interrupts = <12 0>;
> +
> +                       clocks = <&dispcc DISP_CC_MDSS_DP_AUX_CLK>,
> +                                <&dispcc DISP_CC_MDSS_DP_LINK_CLK>,
> +                                <&dispcc DISP_CC_MDSS_DP_LINK_INTF_CLK>,
> +                                <&dispcc DISP_CC_MDSS_DP_PIXEL_CLK>;
> +                       clock-names = "core_aux", "ctrl_link",
> +                                     "ctrl_link_iface", "stream_pixel";
> +                       #clock-cells = <1>;
> +                       assigned-clocks = <&dispcc DISP_CC_MDSS_DP_PIXEL_CLK_SRC>;
> +                       assigned-clock-parents = <&msm_dp 1>;
> +
> +                       data-lanes = <0 1>;

This can and should be left to the board files. At the SoC level my
understanding is that there are four lanes possible, so no need to
artificially limit it here.

> +
> +                       ports {
> +                               #address-cells = <1>;
> +                               #size-cells = <0>;
> +                               port@0 {
> +                                       reg = <0>;
> +                                       dp_in: endpoint {
> +                                               remote-endpoint =
> +                                                        <&dpu_intf0_out>;

I'd prefer these were on one line, regardless of the 80 character line
limit/suggestion.

> +                                       };
> +                               };
> +
> +                               port@1 {
> +                                       reg = <1>;
> +                                       dp_out: endpoint { };
> +                               };
> +                       };
> +               };
> +
>                 dispcc: clock-controller@...0000 {
>                         compatible = "qcom,sc7180-dispcc";
>                         reg = <0 0x0af00000 0 0x200000>;