Re: [PATCHv2 57/56] dt-bindings: display: panel-dsi-cm: convert to YAML

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Sebastian,

Thank you for the patch.

On Thu, Feb 27, 2020 at 09:35:21PM +0100, Sam Ravnborg wrote:
> On Tue, Feb 25, 2020 at 12:53:41PM +0100, Sebastian Reichel wrote:
> > Convert panel-dsi-cm bindings to YAML and add
> > missing properties while at it.
> > 
> > Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
> 
> As saind in previous mail - I prefer to convert ann then patch.
> But end result is the same so OK.

I agree, splitting the patch would be better.

> > ---
> >  .../bindings/display/panel/panel-dsi-cm.txt   | 31 ------
> >  .../bindings/display/panel/panel-dsi-cm.yaml  | 97 +++++++++++++++++++
> >  2 files changed, 97 insertions(+), 31 deletions(-)
> >  delete mode 100644 Documentation/devicetree/bindings/display/panel/panel-dsi-cm.txt
> >  create mode 100644 Documentation/devicetree/bindings/display/panel/panel-dsi-cm.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/display/panel/panel-dsi-cm.txt b/Documentation/devicetree/bindings/display/panel/panel-dsi-cm.txt
> > deleted file mode 100644
> > index f92d5c9adfc5..000000000000
> > --- a/Documentation/devicetree/bindings/display/panel/panel-dsi-cm.txt
> > +++ /dev/null
> > @@ -1,31 +0,0 @@
> > -Generic MIPI DSI Command Mode Panel
> > -===================================
> > -
> > -Required properties:
> > -- compatible: "panel-dsi-cm"
> > -- reg: DSI channel number
> > -
> > -Optional properties:
> > -- label: a symbolic name for the panel
> > -- reset-gpios: panel reset gpio
> > -- te-gpios: panel TE gpio
> > -
> > -Required nodes:
> > -- Video port for DSI input
> > -
> > -Example
> > --------
> > -
> > -lcd0: panel@0 {
> > -	compatible = "tpo,taal", "panel-dsi-cm";
> > -	label = "lcd0";
> > -	reg = <0>;
> > -
> > -	reset-gpios = <&gpio4 6 GPIO_ACTIVE_HIGH>;
> > -
> > -	port {
> > -		lcd0_in: endpoint {
> > -			remote-endpoint = <&dsi1_out_ep>;
> > -		};
> > -	};
> > -};
> > diff --git a/Documentation/devicetree/bindings/display/panel/panel-dsi-cm.yaml b/Documentation/devicetree/bindings/display/panel/panel-dsi-cm.yaml
> > new file mode 100644
> > index 000000000000..ca61171ae145
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/display/panel/panel-dsi-cm.yaml
> > @@ -0,0 +1,97 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/display/panel/panel-dsi-cm.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: DSI command mode panels
> > +
> > +maintainers:
> > +  - Tomi Valkeinen <tomi.valkeinen@ti.com>
> > +  - Sebastian Reichel <sre@kernel.org>
> > +
> > +description: |
> > +  This binding file is a collection of the DSI panels that
> > +  are usually driven in command mode. If no backlight is
> > +  referenced via the optional backlight property, the DSI
> > +  panel is assumed to have native backlight support.

Maybe this sentence could be moved to the description of the backlight
property ? Or would it override the description from panel-common.yaml ?
If so, is there a way in the yaml bindings syntax to extend that
property ?

> > +  The panel may use an OF graph binding for the association
> > +  to the display, or it may be a direct child node of the
> > +  display.
> > +
> > +allOf:
> > +  - $ref: panel-common.yaml#
> > +
> > +properties:
> > +
> > +  compatible:
> > +    enum:
> > +      # compatible must be listed in alphabetical order, ordered by compatible.
> > +      # The description in the comment is mandatory for each compatible.
> > +      - motorola,droid4-panel, panel-dsi-cm
> > +      - nokia,himalaya, panel-dsi-cm
> > +      - tpo,taal, panel-dsi-cm
>
> Please consider to use the following syntax (from memory - may require
> an enum:):
> 
>   compatible:
>     description:
>       Shall contain a panel specific compatible and "panel-dsi-cm"
>       in that order.
>     items:
>       - oneOf:
>           # Maybe add a short description of this panel
>         - motorola,droid4-panel
>           # Maybe add a short description of this panel
> 	- nokia,himalaya
>           # Maybe add a short description of this panel
> 	- tpo,taal
> 
>       - const: panel-dsi-cm
> 
> Then panel-dsi-cm is always specified as a second mandatory compatible.

This is not only nicer, but it's actually correct, while the original
version isn't. The original version would require, for instance,

	compatible = "motorola,droid4-panel, panel-dsi-cm";

and not

	compatible = "motorola,droid4-panel", "panel-dsi-cm";

> > +
> > +  reg:
> > +    maxItems: 1
> > +    description: DSI virtual channel
> > +
> > +  te-gpios:
> > +    maxItems: 1
> > +    description:
> > +      Specifier for a GPIO connected to the panel TE (tearing event) signal.
> > +      The GPIO informs the system, that data should be sent to the display
> > +      on rising edges of the GPIO to avoid (or reduce) tearing effects.
> > +      Falling edge can be supported by inverting the GPIO specifier polarity
> > +      flag.
>
> te-gpios is used by several panels.
> Please add it to panel-common with your nice description.

Possible too late to change this, but shouldn't we really have used

	interrupts = <...>;
	interrupt-names = "te";

?

The TE signal may be connected to an interrupt pin that is not a GPIO.

> With the above addressed:
> Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
> 
> > +
> > +  vddi-supply:
> > +    description:
> > +      Display panels require power to be supplied. While several panels need
> > +      more than one power supply with panel-specific constraints governing the
> > +      order and timings of the power supplies, in many cases a single power
> > +      supply is sufficient, either because the panel has a single power rail, or
> > +      because all its power rails can be driven by the same supply. In that case
> > +      the vddi-supply property specifies the supply powering the panel as a
> > +      phandle to a regulator.
> > +
> > +  vpnl-supply:
> > +    description:
> > +      When the display panel needs a second power supply, this property can be
> > +      used in addition to vddi-supply. Both supplies will be enabled at the
> > +      same time before the panel is being accessed.

Too late for this too, but I wonder if the best practice for this kind
of cases wouldn't be to specify a single supply that would be modelled
by a regulator with multiple inputs.

> > +  width-mm: true
> > +  height-mm: true
> > +  label: true
> > +  rotation: true
> > +  panel-timing: true
> > +  port: true
> > +  reset-gpios: true
> > +  backlight: true
> > +
> > +additionalProperties: false
> > +
> > +required:
> > +  - compatible
> > +  - port

You wrote in the overall description that the panel may have a port node
or may be a child of the DSI controller. Doesn't that make port optional
?

Should we require width-mm and height-mm ?

> > +  - reg
> > +
> > +examples:
> > +  - |
> > +    dsi1@12345678 {
> > +      #address-cells = <1>;
> > +      #size-cells = <0>;
> > +      panel@0 {
> > +        compatible = "tpo,taal", "panel-dsi-cm";
> > +        label = "lcd0";
> > +        reg = <0>;
> > +        reset-gpios = <&gpio4 6 GPIO_ACTIVE_HIGH>;
> > +
> > +        port {
> > +          panel: endpoint {
> > +            remote-endpoint = <&dsi1_out_ep>;
> > +          };
> > +        };
> > +      };
> > +    };

-- 
Regards,

Laurent Pinchart
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel