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From:   Stephen Boyd <swboyd@chromium.org>
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Date:   Thu, 3 Jun 2021 21:35:34 +0000
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Subject: Re: [PATCH v2] arm64/dts/qcom/sc7180: Add Display Port dt node
To:     Bjorn Andersson <bjorn.andersson@linaro.org>, khsieh@codeaurora.org
Cc:     robdclark@gmail.com, sean@poorly.run, vkoul@kernel.org,
        agross@kernel.org, robh+dt@kernel.org, devicetree@vger.kernel.org,
        abhinavk@codeaurora.org, aravindh@codeaurora.org,
        freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org
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Quoting khsieh@codeaurora.org (2021-06-03 14:28:37)
> On 2021-06-03 09:53, Bjorn Andersson wrote:
> > On Thu 03 Jun 11:09 CDT 2021, Kuogee Hsieh wrote:
> >
> >> Add DP device node on sc7180.
> >>
> >> Changes in v2:
> >> -- replace msm_dp with dp
> >> -- replace dp_opp_table with opp_table
> >>
> >
> > I'm sorry for those suggestions, I don't like either one of them.
> >
> > And for everything but changes to the DRM code the changelog goes below
> > the --- line, so it's not part of the git history.
> >
> >> Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
> >> ---
> >>  arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi |  9 ++++
> >>  arch/arm64/boot/dts/qcom/sc7180.dtsi         | 78
> >> ++++++++++++++++++++++++++++
> >>  2 files changed, 87 insertions(+)
> >>
> >> diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> >> b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> >> index 24d293e..40367a2 100644
> >> --- a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> >> +++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> >> @@ -786,6 +786,15 @@ hp_i2c: &i2c9 {
> >>      status = "okay";
> >>  };
> >>
> >> +&dp {
> >> +        status = "okay";
> >> +        pinctrl-names = "default";
> >> +        pinctrl-0 = <&dp_hot_plug_det>;
> >> +        data-lanes = <0 1>;
> >
> > Is it a limitation of the EC in Trogdor that you can only do 2 lanes?
>
> yes,
>

It's not an EC limitation. It's a hardware design decision. We have one
type-c PHY on the sc7180 SoC and we have two type-c ports on the board
so we have decided to only use two lanes for DP and two lanes for USB on
the type-c ports so that both type-c ports work all the time.