linux-kernel - Re: [PATCH v3 1/2] arm64: dts: qcom: add data-lanes and link-freuencies into dp

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Message-ID: <CAA8EJppjMK=SNbnir4QGgVJ5we1UGjrrvG6KJFgcSfRVZZm8sw@mail.gmail.com>
Date:   Fri, 18 Nov 2022 13:01:10 +0200
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Kuogee Hsieh <quic_khsieh@...cinc.com>
Cc:     dri-devel@...ts.freedesktop.org, robdclark@...il.com,
        sean@...rly.run, swboyd@...omium.org, dianders@...omium.org,
        vkoul@...nel.org, daniel@...ll.ch, airlied@...ux.ie,
        agross@...nel.org, bjorn.andersson@...aro.org,
        quic_abhinavk@...cinc.com, quic_sbillaka@...cinc.com,
        freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/2] arm64: dts: qcom: add data-lanes and
 link-freuencies into dp_out endpoint

On Fri, 18 Nov 2022 at 00:50, Kuogee Hsieh <quic_khsieh@...cinc.com> wrote:
>
> Add both data-lanes and link-frequencies property to dp_out endpoint.

Bindings update?
Deprecate the old data-lanes property?

> Also set link-frequencies to 810000 khz at herobrine platform to have
> max link rate limited at 810000 khz (HBR3).

No. As  I stated before, the link-frequencies should list all
supported frequencies (min/max in case the frequencies are
continuous).
Stating just maximum is against the property description.

>
> Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
> ---
>  arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi   |  9 ++++++++-
>  arch/arm64/boot/dts/qcom/sc7180.dtsi           |  5 -----
>  arch/arm64/boot/dts/qcom/sc7280-herobrine.dtsi | 10 +++++++++-
>  arch/arm64/boot/dts/qcom/sc7280.dtsi           |  5 -----
>  4 files changed, 17 insertions(+), 12 deletions(-)
>

[skipped the sc7180 here. All comments noted against sc7280 apply to
sc7180 too].

> diff --git a/arch/arm64/boot/dts/qcom/sc7280-herobrine.dtsi b/arch/arm64/boot/dts/qcom/sc7280-herobrine.dtsi
> index 93e39fc..e8fca18 100644
> --- a/arch/arm64/boot/dts/qcom/sc7280-herobrine.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sc7280-herobrine.dtsi
> @@ -440,7 +440,15 @@ ap_i2c_tpm: &i2c14 {
>         status = "okay";
>         pinctrl-names = "default";
>         pinctrl-0 = <&dp_hot_plug_det>;
> -       data-lanes = <0 1>;
> +       ports {
> +               port@1 {
> +                       reg = <1>;
> +                       dp_out: endpoint {
> +                               data-lanes = <0 1>;
> +                               link-frequencies=<810000>;

Following the existing examples is nice. Not following them is frowned upon.

> +                       };
> +               };
> +       };

Just:

&dp_out {
    data-lanes = <0  1>;
    link-frequencies = /bits/ 64 <160000000 270000000 540000000 810000000>;
};

>  };
>
>  &mdss_mdp {
> diff --git a/arch/arm64/boot/dts/qcom/sc7280.dtsi b/arch/arm64/boot/dts/qcom/sc7280.dtsi
> index a646405..4afe53b 100644
> --- a/arch/arm64/boot/dts/qcom/sc7280.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sc7280.dtsi
> @@ -3899,11 +3899,6 @@
>                                                         remote-endpoint = <&dpu_intf0_out>;
>                                                 };
>                                         };
> -
> -                                       port@1 {
> -                                               reg = <1>;
> -                                               dp_out: endpoint { };
> -                                       };

Please leave it here. It is a part of the SoC, so it should be in SoC dtsi.

>                                 };
>
>                                 dp_opp_table: opp-table {

-- 
With best wishes
Dmitry