Re: [PATCH v2 2/2] dt-bindings: display: simple-framebuffer: Document physical width and height properties

[Rayyan Ansari]

On 22/01/2023 15:36, Rob Herring wrote:
> On Sat, Jan 21, 2023 at 9:36 AM Rayyan Ansari <rayyan@xxxxxxxxx> wrote:
> >
>
> Why do you need this change?
>
> The 'simple-framebuffer' contains data on how the bootloader
> configured the display. The bootloader doesn't configure the display
> size, so this information doesn't belong here. The information should
> already be in the panel node, so also no point in duplicating it here.
>
> > Signed-off-by: Rayyan Ansari <rayyan@xxxxxxxxx>
> > ---
> >   .../devicetree/bindings/display/simple-framebuffer.yaml   | 8 ++++++++
> >   1 file changed, 8 insertions(+)

Hi Rob,

There is the usecase that Hans has mentioned, but I have also mentioned 
another usecase previously.

Adding the width-mm and height-mm properties allows user interfaces such 
as Phosh (https://puri.sm/posts/phosh-overview/) to scale correctly to 
the screen. In my case, a panel node is not available and the 
aforementioned interface is in fact running on the SimpleDRM driver 
(which binds to the simple-framebuffer device).

Here is the device I have tested this patch on, the Lumia 735 phone: 
https://wiki.postmarketos.org/images/c/c3/Lumia_735_Phosh.png
Without this patch, this would appear quite small on the screen.

See https://patchwork.freedesktop.org/patch/519107/?series=113053&rev=1 
for some background info about this patch.

Regards,
--
Rayyan Ansari
https://ansari.sh