linux-kernel - Re: [PATCH v4 2/5] arm64: dts: qcom: sc7280: Add support for eDP panel on CRD

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Date:   Fri, 18 Feb 2022 06:56:01 -0800
From:   Doug Anderson <dianders@...omium.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Sankeerth Billakanti <quic_sbillaka@...cinc.com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        freedreno <freedreno@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Andy Gross <agross@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Rob Clark <robdclark@...il.com>,
        Sean Paul <seanpaul@...omium.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, quic_kalyant@...cinc.com,
        quic_abhinavk@...cinc.com, quic_khsieh@...cinc.com,
        quic_mkrishn@...cinc.com, quic_vproddut@...cinc.com
Subject: Re: [PATCH v4 2/5] arm64: dts: qcom: sc7280: Add support for eDP
 panel on CRD

Hi,

On Thu, Feb 10, 2022 at 4:04 PM Bjorn Andersson
<bjorn.andersson@...aro.org> wrote:
>
> > +&mdss_edp {
> > +     status = "okay";
> > +
> > +     vdda-1p2-supply = <&vreg_l6b_1p2>;
> > +     vdda-0p9-supply = <&vreg_l10c_0p8>;
> > +     /delete-property/ pinctrl-names;
> > +     /delete-property/ pinctrl-0;
>
> If the first device to enable &mdss_edp overwrites pinctrl-{names,0} in
> &mdss_dp and removes the properties in &mdss_edp, I think that's a sign
> that they should not be in the .dtsi in the first place.

Actually, I just looked more carefully here. I think the
"/delete-property" for edp_hpd here is just wrong. I'm pretty sure
that the HPD signal is hooked up on CRD and we actually need it. If
somehow deleting the property helps you then it's probably just
hacking around a bug and relying on the panel to be always powered on,
or something.

I think this gets into some of the stuff in your final patch in this
series. I found that, on my hardware, the panel doesn't come up at all
with that final patch. When I go back to how things were working in an
earlier version of your series, though, I can get things working a
little better (though still not perfect).

-Doug