On Wed, Sep 17, 2014 at 02:52:42PM +0300, Tomi Valkeinen wrote:
> On 27/08/14 17:39, Ajay Kumar wrote:
> > Add documentation for DT properties supported by ps8622/ps8625
> > eDP-LVDS converter.
> >
> > Signed-off-by: Ajay Kumar <ajaykumar.rs@xxxxxxxxxxx>
> > ---
> > .../devicetree/bindings/video/bridge/ps8622.txt | 20 ++++++++++++++++++++
> > 1 file changed, 20 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/video/bridge/ps8622.txt
> >
> > diff --git a/Documentation/devicetree/bindings/video/bridge/ps8622.txt b/Documentation/devicetree/bindings/video/bridge/ps8622.txt
> > new file mode 100644
> > index 0000000..0ec8172
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/video/bridge/ps8622.txt
> > @@ -0,0 +1,20 @@
> > +ps8622-bridge bindings
> > +
> > +Required properties:
> > + - compatible: "parade,ps8622" or "parade,ps8625"
> > + - reg: first i2c address of the bridge
> > + - sleep-gpios: OF device-tree gpio specification for PD_ pin.
> > + - reset-gpios: OF device-tree gpio specification for RST_ pin.
> > +
> > +Optional properties:
> > + - lane-count: number of DP lanes to use
> > + - use-external-pwm: backlight will be controlled by an external PWM
>
> What does this mean? That the backlight support from ps8625 is not used?
> If so, maybe "disable-pwm" or something?
>
> > +
> > +Example:
> > + lvds-bridge@48 {
> > + compatible = "parade,ps8622";
> > + reg = <0x48>;
> > + sleep-gpios = <&gpc3 6 1 0 0>;
> > + reset-gpios = <&gpc3 1 1 0 0>;
> > + lane-count = <1>;
> > + };
> >
>
> I wish all new display component bindings would use the video
> ports/endpoints to describe the connections. It will be very difficult
> to improve the display driver model later if we're missing such critical
> pieces from the DT bindings.
I disagree. Why would we want to burden all devices with a bloated
binding and drivers with parsing a complex graph when it's not even
known that it will be necessary? Evidently this device works fine
using the current binding. Just because there are bindings to describe
ports in a generic way doesn't mean it has to be applied everywhere.
After all the concept of ports/endpoints applies to non-video devices
too, yet we don't require the bindings for those devices to add ports
or endpoints nodes.
Also it won't be very difficult to extend the binding in a backwards
compatible way if that becomes necessary.
One thing that I'd like to see in this binding, though, is how to hook
up the bridge to a panel. However I'm still catching up on mail after
vacation, so perhaps this has already been discussed further down the
thread.
Thierry
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