On Wed, May 25, 2022 at 09:46:24PM +0200, Javier Martinez Canillas wrote:

On 3/10/22 14:11, Dominik Kierner wrote:

...

quoted

# DRM Mode Configuration via Device Tree

In the old fbdev driver, the display modes are hard-coded, which means
for every new display configuration, a new patch needs to be mainlined,
which slows down official Kernel support and
puts burden on the maintainers.
Additionally, with the DRM-subsystem supporting height and length
information, for scaling, this opens up a lot of new combinations.
The SSD1306 for example, is available in multiple resolutions like
128x64 and 96x16 and comes in different sizes per resolution as well.
Just to name a few:
* 128x64 0.96" (22x11mm)
* 128x64 1.3" (30x15mm)
* 96x16 0.69" (18x3mm)

quoted

Instead of hard-coding, I would suggest something along the lines of

of_get_drm_display_mode().
The displays won't need to support multiple modes at the same time,
let alone support for switching between them,
so the one-time invocation of this expensive function might be worth it. 
maybe a new and simpler function that could be named:
of_get_drm_display_mode_simple()

This makes sense to me as well.

What about non-OF platforms? Please, do not spread OF-only interfaces,
and use fwnode instead.

quoted

Providing a mode could later prove useful for a conversion to
drm_panel, if that is feasible.

But for a function like this, I have to chicken out.

-- 
With Best Regards,
Andy Shevchenko