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Date:   Sat, 27 Jul 2019 04:59:25 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Sam Ravnborg <sam@ravnborg.org>
Cc:     Guido =?utf-8?Q?G=C3=BCnther?= <agx@sigxcpu.org>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Lee Jones <lee.jones@linaro.org>,
        dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Robert Chiras <robert.chiras@nxp.com>
Subject: Re: [PATCH 2/3] dt-bindings: display/bridge: Add binding for IMX NWL
 mipi dsi host controller
Message-ID: <20190727015925.GB4902@pendragon.ideasonboard.com>
References: <cover.1563983037.git.agx@sigxcpu.org>
 <70a5c6617936a4a095e7608b96e3f9fae5ddfbb1.1563983037.git.agx@sigxcpu.org>
 <20190726092315.GA9754@ravnborg.org>
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Hello,

On Fri, Jul 26, 2019 at 11:23:15AM +0200, Sam Ravnborg wrote:
> On Wed, Jul 24, 2019 at 05:52:25PM +0200, Guido Günther wrote:
> > The Northwest Logic MIPI DSI IP core can be found in NXPs i.MX8 SoCs.
> > 
> > Signed-off-by: Guido Günther <agx@sigxcpu.org>
> > ---
> >  .../bindings/display/bridge/imx-nwl-dsi.txt   | 89 +++++++++++++++++++
> 
> New binding. Any chance we can get this in yaml format?
> This is the way forward and we have to convert the file anyway.
> 
> None of the other bridges use yaml format, but someone has to be the
> first.
> 
> >  1 file changed, 89 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/display/bridge/imx-nwl-dsi.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/display/bridge/imx-nwl-dsi.txt b/Documentation/devicetree/bindings/display/bridge/imx-nwl-dsi.txt
> > new file mode 100644
> > index 000000000000..288fdb726d5a
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/display/bridge/imx-nwl-dsi.txt
> > @@ -0,0 +1,89 @@
> > +Northwest Logic MIPI-DSI on imx SoCs
> > +=====================================
> > +
> > +NWL MIPI-DSI host controller found on i.MX8 platforms. This is a
> > +dsi bridge for the for the NWL MIPI-DSI host.
> 
> To my best understanding a bridge is something that converts from one
> format to another format.
> Something that in the drm world are connected to an encoder.
> 
> I do not know the HW here - but from this very brif description this
> sounds more like a display controller and not a bridge?

I would call it an encoder, that's the term usually employed for such
devices (similar to HDMI encoder).

> > +
> > +Required properties:
> > +- compatible: 		"fsl,<chip>-nwl-dsi"
> > +	The following strings are expected:
> > +			"fsl,imx8mq-nwl-dsi"
> > +- reg: 			the register range of the MIPI-DSI controller
> > +- interrupts: 		the interrupt number for this module
> > +- clock, clock-names: 	phandles to the MIPI-DSI clocks
> > +	The following clocks are expected on all platforms:
> > +		"core"    - DSI core clock
> > +		"tx_esc"  - TX_ESC clock (used in escape mode)
> > +		"rx_esc"  - RX_ESC clock (used in escape mode)
> > +		"phy_ref" - PHY_REF clock. Clock is managed by the phy. Only
> > +                            used to read the clock rate.
> > +- assigned-clocks:	phandles to clocks that require initial configuration
> > +- assigned-clock-rates:	rates of the clocks that require initial configuration
> > +	The following clocks need to have an initial configuration:
> > +	"tx_esc" (20 MHz) and "rx_esc" (80 Mhz).
> > +- phys: 		phandle to the phy module representing the DPHY
> > +			inside the MIPI-DSI IP block
> > +- phy-names: 		should be "dphy"
> > +
> > +Optional properties:
> > +- power-domains 	phandle to the power domain
> > +- src			phandle to the system reset controller (required on
> > +			i.MX8MQ)
> Name is not very descriptive.
> Other bindings seems to use "resets" here?
> 
> > +- mux-sel		phandle to the MUX register set (required on i.MX8MQ)
> > +- assigned-clock-parents phandles to parent clocks that needs to be assigned as
> > +			parents to clocks defined in assigned-clocks
> > +
> > +Example:
> > +	mipi_dsi: mipi_dsi@30a00000 {
> > +		#address-cells = <1>;
> > +		#size-cells = <0>;
> > +		compatible = "fsl,imx8mq-nwl-dsi";
> > +		reg = <0x30A00000 0x300>;
> > +		clocks = <&clk IMX8MQ_CLK_DSI_CORE>,
> > +			 <&clk IMX8MQ_CLK_DSI_AHB>,
> > +			 <&clk IMX8MQ_CLK_DSI_IPG_DIV>,
> > +			 <&clk IMX8MQ_CLK_DSI_PHY_REF>;
> > +		clock-names = "core", "rx_esc", "tx_esc", "phy_ref";
> > +		assigned-clocks = <&clk IMX8MQ_CLK_DSI_AHB>,
> > +				  <&clk IMX8MQ_CLK_DSI_CORE>,
> > +				  <&clk IMX8MQ_CLK_DSI_IPG_DIV>;
> > +		assigned-clock-parents = <&clk IMX8MQ_SYS1_PLL_80M>,
> > +					 <&clk IMX8MQ_SYS1_PLL_266M>;
> > +		assigned-clock-rates = <80000000>,
> > +				       <266000000>,
> > +				       <20000000>;
> > +		interrupts = <GIC_SPI 34 IRQ_TYPE_LEVEL_HIGH>;
> > +		power-domains = <&pgc_mipi>;
> > +		src = <&src>;
> > +		mux-sel = <&iomuxc_gpr>;
> > +		phys = <&dphy>;
> > +		phy-names = "dphy";
> > +		status = "okay";
> I recall status should not be included in examples.
> 
> > +
> > +		panel@0 {
> > +			compatible = "...";
> > +			port {
> > +			     panel_in: endpoint {
> > +				       remote-endpoint = <&mipi_dsi_out>;
> > +			     };
> > +			};
> > +		};
> > +
> > +		ports {
> > +		      #address-cells = <1>;
> > +		      #size-cells = <0>;
> > +
> > +		      port@0 {
> > +			     reg = <0>;
> > +			     mipi_dsi_in: endpoint {
> > +					  remote-endpoint = <&dcss_disp0_mipi_dsi>;
> > +			     };
> > +		      };
> > +		      port@1 {
> > +			     reg = <1>;
> > +			     mipi_dsi_out: endpoint {
> > +					   remote-endpoint = <&panel_in>;
> > +			     };
> > +		      };
> > +		};
> > +	};

-- 
Regards,

Laurent Pinchart