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[209.85.219.174]) by smtp.gmail.com with ESMTPSA id l8sm1622746qtr.19.2021.03.24.08.32.12 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 Mar 2021 08:32:12 -0700 (PDT) Received: by mail-yb1-f174.google.com with SMTP id l15so3479565ybm.0 for ; Wed, 24 Mar 2021 08:32:12 -0700 (PDT) X-Received: by 2002:a25:b443:: with SMTP id c3mr5809966ybg.32.1616599932107; Wed, 24 Mar 2021 08:32:12 -0700 (PDT) MIME-Version: 1.0 References: <20210324025534.1837405-1-swboyd@chromium.org> In-Reply-To: <20210324025534.1837405-1-swboyd@chromium.org> From: Doug Anderson Date: Wed, 24 Mar 2021 08:32:00 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] arm64: dts: qcom: trogdor: Add no-hpd to DSI bridge node To: Stephen Boyd Cc: Andy Gross , Bjorn Andersson , LKML , linux-arm-msm , Laurent Pinchart Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Tue, Mar 23, 2021 at 7:55 PM Stephen Boyd wrote: > > We should indicate that we're not using the HPD pin on this device, per > the binding document. Otherwise if code in the future wants to enable > HPD in the bridge when this property is absent we'll be wasting power > powering hpd when we don't use it on trogdor boards. We didn't notice > this before because the kernel driver blindly disables hpd, but that > won't be true for much longer. > > Cc: Laurent Pinchart > Cc: Douglas Anderson > Fixes: 7ec3e67307f8 ("arm64: dts: qcom: sc7180-trogdor: add initial trogdor and lazor dt") > Signed-off-by: Stephen Boyd > --- > arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi > index 07c8b2c926c0..298af6d7fb4a 100644 > --- a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi > +++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi > @@ -595,6 +595,8 @@ sn65dsi86_bridge: bridge@2d { > clocks = <&rpmhcc RPMH_LN_BB_CLK3>; > clock-names = "refclk"; > > + no-hpd; > + Sigh. I can't believe that I added this for cheza in commit 0d1ce0d14bd7 ("arm64: dts: sdm845: Add "no-hpd" to sn65dsi86 on cheza") but forgot trogdor. Thanks. Reviewed-by: Douglas Anderson NOTE: if you were feeling charitable you might consider sending a patch for "sdm850-lenovo-yoga-c630.dts" as well. I don't personally know if HPD is hooked up on that system, but presumably even if it is it's just as useless as it is on other systems where the bridge is used for eDP. If nothing else setting it preserves existing behavior. Someone (I forget who) requested that I word the bindings specifically to say that "no-hpd" was OK to specify in cases like that, since the bindings say: > Set if the HPD line on the bridge isn't hooked up to anything or is > otherwise unusable. -Doug