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[24.155.109.49]) by smtp.gmail.com with ESMTPSA id q63sm128029oic.15.2021.06.02.11.00.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Jun 2021 11:00:18 -0700 (PDT) Received: (nullmailer pid 3674811 invoked by uid 1000); Wed, 02 Jun 2021 18:00:17 -0000 Date: Wed, 2 Jun 2021 13:00:17 -0500 From: Rob Herring To: Douglas Anderson Subject: Re: [PATCH v8 01/11] dt-bindings: display: simple: List hpd properties in panel-simple Message-ID: <20210602180017.GA3674744@robh.at.kernel.org> References: <20210525000159.3384921-1-dianders@chromium.org> <20210524165920.v8.1.Ieb731d23680db4700cc41fe51ccc73ba0b785fb7@changeid> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210524165920.v8.1.Ieb731d23680db4700cc41fe51ccc73ba0b785fb7@changeid> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Neil Armstrong , David Airlie , dri-devel@lists.freedesktop.org, Bjorn Andersson , Andrzej Hajda , Thierry Reding , Laurent Pinchart , Sam Ravnborg , robdclark@chromium.org, Stanislav Lisovskiy , Thierry Reding , devicetree@vger.kernel.org, Jonas Karlman , linux-arm-msm@vger.kernel.org, Stephen Boyd , Rob Herring , Steev Klimaszewski , linux-kernel@vger.kernel.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mon, 24 May 2021 17:01:49 -0700, Douglas Anderson wrote: > The HPD (Hot Plug Detect) signal is present in many (probably even > "most") eDP panels. For eDP, this signal isn't actually used for > detecting hot-plugs of the panel but is more akin to a "panel ready" > signal. After you provide power to the panel, panel timing diagrams > typically say that you should wait for HPD to be asserted (or wait a > fixed amount of time) before talking to the panel. > > The panel-simple bindings describes many eDP panels and many of these > panels provide the HPD signal. We should add the HPD-related > properties to the panel-simple bindings. The HPD properties are > actually defined in panel-common.yaml, so adding them here just > documents that they are OK for panels handled by the panel-simple > bindings. > > NOTE: whether or not we'd include HPD properties in the panel node is > more a property of the board design than the panel itself. For most > boards using these eDP panels everything "magically" works without > specifying any HPD properties and that's been why we haven't needed to > allow the HPD properties earlier. On these boards the HPD signal goes > directly to a dedicated "HPD" input to the eDP controller and this > connection doesn't need to be described in the device tree. The only > time the HPD properties are needed in the device tree are if HPD is > hooked up to a GPIO or if HPD is normally on the panel but isn't used > on a given board. That means that if we don't allow the HPD properties > in panel-simple then one could argue that we've got to boot all eDP > panels (or at least all those that someone could conceivably put on a > system where HPD goes to a GPIO or isn't hooked up) from panel-simple. > > Signed-off-by: Douglas Anderson > --- > > Changes in v8: > - Explain better why HPD needs to be in panel-simple in commit msg. > > Changes in v7: > - List hpd properties bindings patch new for v7. > > .../devicetree/bindings/display/panel/panel-simple.yaml | 2 ++ > 1 file changed, 2 insertions(+) > Reviewed-by: Rob Herring