Re: [PATCH/RFC 4/6] dt-bindings: display: rockchip: dw-hdmi: Convert binding to YAML

From: Maxime Ripard <maxime@cerno.tech>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>,
	devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linux-renesas-soc@vger.kernel.org,
	Rob Herring <robh+dt@kernel.org>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	Mark Yao <mark.yao@rock-chips.com>,
	Sandy Huang <hjc@rock-chips.com>, Chen-Yu Tsai <wens@csie.org>
Subject: Re: [PATCH/RFC 4/6] dt-bindings: display: rockchip: dw-hdmi: Convert binding to YAML
Date: Mon, 6 Apr 2020 19:09:15 +0200	[thread overview]
Message-ID: <20200406170915.x2ztz4q446h6vx2y@gilmour.lan> (raw)
In-Reply-To: <20200406111927.GD4757@pendragon.ideasonboard.com>

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On Mon, Apr 06, 2020 at 02:19:27PM +0300, Laurent Pinchart wrote:
> Hi Maxime,
>
> On Mon, Apr 06, 2020 at 10:00:32AM +0200, Maxime Ripard wrote:
> > On Mon, Apr 06, 2020 at 02:39:33AM +0300, Laurent Pinchart wrote:
> > > Convert the Rockchip HDMI TX text binding to YAML.
> > >
> > > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> > > ---
> > >  .../display/rockchip/dw_hdmi-rockchip.txt     |  74 --------
> > >  .../display/rockchip/rockchip,dw-hdmi.yaml    | 178 ++++++++++++++++++
> > >  2 files changed, 178 insertions(+), 74 deletions(-)
> > >  delete mode 100644 Documentation/devicetree/bindings/display/rockchip/dw_hdmi-rockchip.txt
> > >  create mode 100644 Documentation/devicetree/bindings/display/rockchip/rockchip,dw-hdmi.yaml
> > >
> > > diff --git a/Documentation/devicetree/bindings/display/rockchip/dw_hdmi-rockchip.txt b/Documentation/devicetree/bindings/display/rockchip/dw_hdmi-rockchip.txt
> > > deleted file mode 100644
> > > index 3d32ce137e7f..000000000000
> > > --- a/Documentation/devicetree/bindings/display/rockchip/dw_hdmi-rockchip.txt
> > > +++ /dev/null
> > > @@ -1,74 +0,0 @@
> > > -Rockchip DWC HDMI TX Encoder
> > > -============================
> > > -
> > > -The HDMI transmitter is a Synopsys DesignWare HDMI 1.4 TX controller IP
> > > -with a companion PHY IP.
> > > -
> > > -These DT bindings follow the Synopsys DWC HDMI TX bindings defined in
> > > -Documentation/devicetree/bindings/display/bridge/dw_hdmi.txt with the
> > > -following device-specific properties.
> > > -
> > > -
> > > -Required properties:
> > > -
> > > -- compatible: should be one of the following:
> > > -		"rockchip,rk3228-dw-hdmi"
> > > -		"rockchip,rk3288-dw-hdmi"
> > > -		"rockchip,rk3328-dw-hdmi"
> > > -		"rockchip,rk3399-dw-hdmi"
> > > -- reg: See dw_hdmi.txt.
> > > -- reg-io-width: See dw_hdmi.txt. Shall be 4.
> > > -- interrupts: HDMI interrupt number
> > > -- clocks: See dw_hdmi.txt.
> > > -- clock-names: Shall contain "iahb" and "isfr" as defined in dw_hdmi.txt.
> > > -- ports: See dw_hdmi.txt. The DWC HDMI shall have a single port numbered 0
> > > -  corresponding to the video input of the controller. The port shall have two
> > > -  endpoints, numbered 0 and 1, connected respectively to the vopb and vopl.
> > > -- rockchip,grf: Shall reference the GRF to mux vopl/vopb.
> > > -
> > > -Optional properties
> > > -
> > > -- ddc-i2c-bus: The HDMI DDC bus can be connected to either a system I2C master
> > > -  or the functionally-reduced I2C master contained in the DWC HDMI. When
> > > -  connected to a system I2C master this property contains a phandle to that
> > > -  I2C master controller.
> > > -- clock-names: See dw_hdmi.txt. The "cec" clock is optional.
> > > -- clock-names: May contain "cec" as defined in dw_hdmi.txt.
> > > -- clock-names: May contain "grf", power for grf io.
> > > -- clock-names: May contain "vpll", external clock for some hdmi phy.
> > > -- phys: from general PHY binding: the phandle for the PHY device.
> > > -- phy-names: Should be "hdmi" if phys references an external phy.
> > > -
> > > -Optional pinctrl entry:
> > > -- If you have both a "unwedge" and "default" pinctrl entry, dw_hdmi
> > > -  will switch to the unwedge pinctrl state for 10ms if it ever gets an
> > > -  i2c timeout.  It's intended that this unwedge pinctrl entry will
> > > -  cause the SDA line to be driven low to work around a hardware
> > > -  errata.
> > > -
> > > -Example:
> > > -
> > > -hdmi: hdmi@ff980000 {
> > > -	compatible = "rockchip,rk3288-dw-hdmi";
> > > -	reg = <0xff980000 0x20000>;
> > > -	reg-io-width = <4>;
> > > -	ddc-i2c-bus = <&i2c5>;
> > > -	rockchip,grf = <&grf>;
> > > -	interrupts = <GIC_SPI 103 IRQ_TYPE_LEVEL_HIGH>;
> > > -	clocks = <&cru  PCLK_HDMI_CTRL>, <&cru SCLK_HDMI_HDCP>;
> > > -	clock-names = "iahb", "isfr";
> > > -	ports {
> > > -		hdmi_in: port {
> > > -			#address-cells = <1>;
> > > -			#size-cells = <0>;
> > > -			hdmi_in_vopb: endpoint@0 {
> > > -				reg = <0>;
> > > -				remote-endpoint = <&vopb_out_hdmi>;
> > > -			};
> > > -			hdmi_in_vopl: endpoint@1 {
> > > -				reg = <1>;
> > > -				remote-endpoint = <&vopl_out_hdmi>;
> > > -			};
> > > -		};
> > > -	};
> > > -};
> > > diff --git a/Documentation/devicetree/bindings/display/rockchip/rockchip,dw-hdmi.yaml b/Documentation/devicetree/bindings/display/rockchip/rockchip,dw-hdmi.yaml
> > > new file mode 100644
> > > index 000000000000..8ff544ae0ac2
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/display/rockchip/rockchip,dw-hdmi.yaml
> > > @@ -0,0 +1,178 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/display/rockchip/rockchip,dw-hdmi.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Rockchip DWC HDMI TX Encoder
> > > +
> > > +maintainers:
> > > +  - Mark Yao <mark.yao@rock-chips.com>
> > > +
> > > +description: |
> > > +  The HDMI transmitter is a Synopsys DesignWare HDMI 1.4 TX controller IP
> > > +  with a companion PHY IP.
> > > +
> > > +allOf:
> > > +  - $ref: ../bridge/synopsys,dw-hdmi.yaml#
> > > +
> > > +properties:
> > > +  compatible:
> > > +    enum:
> > > +      - rockchip,rk3228-dw-hdmi
> > > +      - rockchip,rk3288-dw-hdmi
> > > +      - rockchip,rk3328-dw-hdmi
> > > +      - rockchip,rk3399-dw-hdmi
> > > +
> > > +  reg: true
> > > +
> > > +  reg-io-width:
> > > +    const: 4
> > > +
> > > +  clocks:
> > > +    minItems: 2
> > > +    maxItems: 5
> > > +    items:
> > > +      - description: The bus clock for either AHB and APB
> > > +      - description: The internal register configuration clock
> > > +      - description: The HDMI CEC controller main clock
> > > +      - description: Power for GRF IO
> > > +      - description: External clock for some HDMI PHY
> > > +
> > > +  clock-names:
> > > +    minItems: 2
> > > +    maxItems: 5
> > > +    items:
> > > +      - const: iahb
> > > +      - const: isfr
> > > +      - enum:
> > > +        - cec
> > > +        - grf
> > > +        - vpll
> > > +      - enum:
> > > +        - cec
> > > +        - grf
> > > +        - vpll
> > > +      - enum:
> > > +        - cec
> > > +        - grf
> > > +        - vpll
> >
> > IIRC Rob wanted us to standardize the order of the clocks if possible,
> > since it's a pain to support properly here, and your description won't
> > match what you describe here either (and in general it's just a best
> > practice), so if all your DTs have the same order you should just set
> > that order in stone.
>
> But how do we handle the case where any of the cec, grf and vpll clocks
> can be set ? Assuming, for instance, that
>
> 	clock-names = "iahb", "isfr", "cec";
> 	clock-names = "iahb", "isfr", "vpll";
> 	clock-names = "iahb", "isfr", "cec", "vpll";
>
> would all be valid.

It would be painful then...

The easiest way to do so would be to simply use an enum there, and not
bother checking the array at all. You'll get a warning if there's
multiple occurences of the same string, and I guess that's what you
would be really concerned about.

However, now that I think about it, what's the interaction between the
generic binding and this one when it comes to the third clock? The
generic one expects it to be cec, and here you have other options?

Maxime

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