Messages in this thread | | | Date | Tue, 24 Jan 2023 22:19:09 +0000 | Subject | Re: [PATCH v2 2/2] dt-bindings: display: simple-framebuffer: Document physical width and height properties | From | Rayyan Ansari <> |
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On 23/01/2023 17:53, Rob Herring wrote: > On Sun, Jan 22, 2023 at 05:25:38PM +0000, Rayyan Ansari wrote: >> On 22/01/2023 15:36, Rob Herring wrote: >>> On Sat, Jan 21, 2023 at 9:36 AM Rayyan Ansari <rayyan@ansari.sh> 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@ansari.sh> >>>> --- >>>> .../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). > > Why is the panel node not available? Why not add it? Presumably it is > not there because you aren't (yet) using the simple-panel driver (and > others that would need). But presumably you will eventually as I'd > imagine turning the screen off and back on might be a desired feature.
It requires more than using the simple-panel driver: first the SoC side display hardware needs to be brought up, then a panel driver that implements the proper DCS initialisation sequence needs to be written (which is currently not fully known).
> > So why add a temporary DT property that's tied to your *current* kernel? > The DT should not be tightly coupled to the kernel.
I'm not sure what you mean by it being "tightly coupled" to the kernel.
> > Rob
-- Rayyan Ansari https://ansari.sh
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