On Mon, Feb 4, 2019 at 2:24 AM Thierry Reding <thierry.reding@xxxxxxxxx> wrote: > > On Mon, Feb 04, 2019 at 12:13:55AM -0800, Vasily Khoruzhick wrote: > > On Sun, Feb 3, 2019 at 11:43 PM Thierry Reding <thierry.reding@xxxxxxxxx> wrote: > > > > > > On Sun, Feb 03, 2019 at 10:54:57AM -0800, Vasily Khoruzhick wrote: > > > > eDP panels usually have EDID EEPROM, so there's no need to define panel > > > > width/height or any modes/timings in dts. But this panel still may have > > > > regulator and/or backlight. > > > > > > > > Signed-off-by: Vasily Khoruzhick <anarsoul@xxxxxxxxx> > > > > --- > > > > .../devicetree/bindings/display/panel/panel-edp.txt | 7 +++++++ > > > > 1 file changed, 7 insertions(+) > > > > create mode 100644 Documentation/devicetree/bindings/display/panel/panel-edp.txt > > > > > > Please don't try to make panels look more generic than they really are. > > > You're going to have to provide a compatible string for your device that > > > is more specific than "panel-edp". You claim that you don't need any > > > extra information that is panel specific, but you don't know that now. > > > We have in the past thought that we didn't need things like prepare > > > delay, but then we ran into situations where we did need them. > > > > > > Just do what everybody else does. Provide a specific compatible string > > > and match on that in the panel-simple driver. Even if you can read all > > > the video timings from an EDID EEPROM, you can still provide a mode in > > > the panel descriptor to serve as a fallback if for example the EEPROM > > > is faulty on some device. > > > > 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 can be a pain to manage especially if panels are swapped run to run with 2nd sources. I think it is perfectly fine to have a generic-ish fallback as long as it is just that, a fallback. If the panel has quirks, then you'd better make sure the firmware is stuffing in the right compatibles or that you can update the firmware. Rob
