On Mon, Feb 04, 2019 at 08:11:05AM -0800, Vasily Khoruzhick wrote: > On Mon, Feb 4, 2019 at 12:24 AM Thierry Reding <thierry.reding@xxxxxxxxx> 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
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