Re: [PATCH 2/3] dt-bindings: new binding for Ilitek ILI9341 display panels

[David Lechner]

On 05/19/2018 08:37 AM, Noralf TrÃnnes wrote:
> Den 15.05.2018 03.43, skrev David Lechner:
> > This adds a new binding for Ilitek ILI9341 display panels. It includes
> > a compatible string for one display (more can be added in the future).
> >
> > The vendor prefix "noname" is used because the vendor is not known.
> > The YX240QV29-T panel[1] is found, for example, in an Adafruit breakout
> > board[2] and in Mindsensors' PiStorms[3].
> >
> > [1]: https://cdn-learn.adafruit.com/assets/assets/000/046/879/original/SPEC-YX240QV29-T_Rev.A__1_.pdf
> > [2]: https://www.adafruit.com/product/2478
> > [3]: http://www.mindsensors.com/stem-with-robotics/13-pistorms-v2-base-kit-raspberry-pi-brain-for-lego-robot
> >
> > Signed-off-by: David Lechner <david@xxxxxxxxxxxxxx>
> > ---
> > Â .../bindings/display/ilitek,ili9341.txtÂÂÂÂÂÂ | 27 +++++++++++++++++++
> > Â 1 file changed, 27 insertions(+)
> > Â create mode 100644 Documentation/devicetree/bindings/display/ilitek,ili9341.txt
> >
> > diff --git a/Documentation/devicetree/bindings/display/ilitek,ili9341.txt b/Documentation/devicetree/bindings/display/ilitek,ili9341.txt
> > new file mode 100644
> > index 000000000000..0fc90b2dd732
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/display/ilitek,ili9341.txt
> > @@ -0,0 +1,27 @@
> > +Ilitek ILI9341 display panels
> > +
> > +This binding is for display panels using an Ilitek ILI9341 controller in SPI
> > +mode.
> > +
> > +Required properties:
> > +- compatible:ÂÂÂ "noname,yx240qv29", "ilitek,ili9341"
>
> Calling a vendor 'noname' looks a bit odd and AFAICT it isn't used by
> any other binding. A google search always mentions Adafruit in
> connection with this panel, so I suggest we use Adafruit as vendor.

I was hoping that someone might know the correct vendor, but barring that,
I agree that adafruit is probably the best choice.

> I don't think we should use "ilitek,ili9341" as an option/fallback,
> because panels varies in resolution (rarely) and initialization. A
> generic ili9341 driver would probably not work with a random new panel.

I'm just following the precedent set in the other bindings for similar
displays that I have already done.

References:
* https://patchwork.freedesktop.org/patch/194648/
* https://patchwork.freedesktop.org/patch/195320/

I agree that it is probably not super-useful as a fallback. On the other
hand, the vendors and models for these displays are pretty obscure and
I think having the more well-known controller name _somewhere_ is useful.


> > +- dc-gpios:ÂÂÂ D/C pin
> > +- reset-gpios:ÂÂÂ Reset pin
> > +
> > +The node for this driver must be a child node of a SPI controller, hence
> > +all mandatory properties described in ../spi/spi-bus.txt must be specified.
> > +
> > +Optional properties:
> > +- rotation:ÂÂÂ panel rotation in degrees counter clockwise (0,90,180,270)
> > +- backlight:ÂÂÂ phandle of the backlight device attached to the panel
>
> You forgot to mention the regulator that you support in the driver.
>
> Noralf.
>
> > +
> > +Example:
> > +ÂÂÂ display@0{
> > +ÂÂÂÂÂÂÂ compatible = "noname,yx240qv29", "ilitek,ili9341";
> > +ÂÂÂÂÂÂÂ reg = <0>;
> > +ÂÂÂÂÂÂÂ spi-max-frequency = <32000000>;
> > +ÂÂÂÂÂÂÂ dc-gpios = <&gpio0 9 GPIO_ACTIVE_HIGH>;
> > +ÂÂÂÂÂÂÂ reset-gpios = <&gpio0 8 GPIO_ACTIVE_HIGH>;
> > +ÂÂÂÂÂÂÂ rotation = <270>;
> > +ÂÂÂÂÂÂÂ backlight = <&backlight>;
> > +ÂÂÂ };