From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH RESEND v2 08/12] dt-bindings: add binding for generic eDP panel Date: Mon, 4 Feb 2019 17:27:19 +0100 Message-ID: <20190204162719.GC25476@ulmo> References: <20190203185501.8958-1-anarsoul@gmail.com> <20190203185501.8958-9-anarsoul@gmail.com> <20190204074350.GC16448@ulmo> <20190204082353.GE19087@ulmo> Reply-To: thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Pk6IbRAofICFmK5e" Return-path: Sender: linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org Content-Disposition: inline In-Reply-To: List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: Vasily Khoruzhick Cc: David Airlie , Daniel Vetter , Rob Herring , Mark Rutland , Maxime Ripard , Chen-Yu Tsai , Archit Taneja , Andrzej Hajda , Laurent Pinchart , Icenowy Zheng , Sean Paul , dri-devel , devicetree , arm-linux , linux-sunxi List-Id: devicetree@vger.kernel.org --Pk6IbRAofICFmK5e Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline On Mon, Feb 04, 2019 at 08:11:05AM -0800, Vasily Khoruzhick wrote: > On Mon, Feb 4, 2019 at 12:24 AM Thierry Reding wrote: > > > > > > Pinebook used several 768p panels that have slightly different timings > > > and recent batch uses 1080p panel. > > > > > > What panel descriptor should I use as fallback? > > > > You don't use panel descriptors as fallback. The simple-panel driver > > will bind to a panel device and use the corresponding descriptor. If > > your device tree contains the correct information, the descriptor is > > correct for the panel you have. > > > > In other words you need to ensure that you have the correct panel in > > device tree for the board that you're using. This is exactly the same > > thing as for other devices. > > > > One way to to this is to have separate device trees for each variant > > of the board that you want to support. Another variant may be to have > > a common device tree and then have some early firmware update the DTB > > with the correct panel information. > > That defeats the purpose of using eDP panels. Panel can identify > itself and report what timings it supports. > > If we use separate DTBs then users will have to figure out what panel > is installed in their hardware and use appropriate software image - > that's something I'd like to avoid. > > I can add a descriptor for something like "pinebook eDP panel" if it > works for you, but it won't have any display timings in it. I'd like to point you to this: http://sietch-tagr.blogspot.com/2016/04/display-panels-are-not-special.html it addresses some of your questions. Hopefully that will also help you understand that this isn't only about display timings. Thierry --Pk6IbRAofICFmK5e--