Re: [PATCH RESEND v2 08/12] dt-bindings: add binding for generic eDP panel

Vasily Khoruzhick
2019-02-04T16:11:05Z

On Mon, Feb 4, 2019 at 12:24 AM Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 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.