display band (display area vs real visible area)

[Daniel Stone]

Hi,

On Tue, 21 Mar 2023 at 11:24, Jani Nikula <jani.nikula at linux.intel.com> wrote:
> On Tue, 21 Mar 2023, Michael Nazzareno Trimarchi <michael at amarulasolutions.com> wrote:
> > On Tue, Mar 21, 2023 at 11:43 AM Jani Nikula
> > <jani.nikula at linux.intel.com> wrote:
> >> On Tue, 21 Mar 2023, Michael Nazzareno Trimarchi <michael at amarulasolutions.com> wrote:
> >> > I would like to know the best approach in the graphics subsystem how
> >> > deal with panels where the display area is different from the visible
> >> > area because the display has a band left and right. I have already
> >> > done the drm driver for the panel but from userspace point of view
> >> > it's a pain to deal in wayland for input device and output device. Do
> >> > you have any suggestions?
> >>
> >> Do you have the EDID for the panel?
> >
> > mipi->panel so should not have edid
>
> That's the kind of information you'd expect in the original question. ;)
>
> I've done that sort of thing in the past, but not sure if it would fly
> upstream. Basically the kernel driver would lie about the resolution to
> userspace, and handle the centering and the bands internally. In my
> case, the DSI command mode panel in question had commands to set the
> visible area, so the driver didn't have to do all that much extra to
> make it happen.

There have been some threads - mostly motivated by MacBooks and the
Asahi team - about creating a KMS property to express invisible areas.
This would be the same thing, and the userspace ecosystem will pick it
up when the kernel exposes it.

Cheers,
Daniel