[PATCH 1/5] dt-bindings: display: panel-dpi: Add bits-per-color property

[Chen-Yu Tsai]

On Thu, Jul 16, 2020 at 4:00 PM Maxime Ripard <maxime at cerno.tech> wrote:
>
> On Tue, Jul 14, 2020 at 03:13:01PM +0800, Chen-Yu Tsai wrote:
> > From: Chen-Yu Tsai <wens at csie.org>
> >
> > Some LCD panels do not support 24-bit true color, or 8bits per channel
> > RGB. Many low end ones only support up to 6 bits per channel natively.
> >
> > Add a device tree property to describe the native bit depth of the
> > panel. This is separate from the bus width or format of the connection
> > to the display output.
> >
> > Signed-off-by: Chen-Yu Tsai <wens at csie.org>
> > ---
> >  .../devicetree/bindings/display/panel/panel-dpi.yaml          | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/display/panel/panel-dpi.yaml b/Documentation/devicetree/bindings/display/panel/panel-dpi.yaml
> > index 0cd74c8dab42..8eb013fb1969 100644
> > --- a/Documentation/devicetree/bindings/display/panel/panel-dpi.yaml
> > +++ b/Documentation/devicetree/bindings/display/panel/panel-dpi.yaml
> > @@ -26,6 +26,9 @@ properties:
> >    height-mm: true
> >    label: true
> >    panel-timing: true
> > +  bits-per-color:
> > +    description:
> > +      Shall contain an integer describing the number of bits per color.
>
> You should specify its type (u32), range (1-8 I guess?) and default
> value (which seems to be 8).

Ok.

> Also, it's not unusual to have a different number of bits per color,
> like for 16 bits panels where we usually use RGB565. I guess we could
> make that an array?

So for different number of bits per color, I'm not sure whether that's
a function of the panel itself, or the bus format. I don't really have
any 16-bit panels on hand. As it stands DRM only handles a common color
depth.

ChenYu