linux-kernel - Re: [V2, 4/5] Documentation: dt-bindings: Document bindings for DW MIPI CSI-2 Host

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Message-ID: <1932462.yjy0pN2BsW@avalon>
Date:   Thu, 20 Sep 2018 16:24:54 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Luis Oliveira <Luis.Oliveira@...opsys.com>
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Joao.Pinto@...opsys.com, festevam@...il.com,
        Luis Oliveira <luis.oliveira@...opsys.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        Arnd Bergmann <arnd@...db.de>,
        Jacob Chen <jacob-chen@...wrt.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Keiichi Watanabe <keiichiw@...omium.org>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Todor Tomov <todor.tomov@...aro.org>,
        devicetree@...r.kernel.org
Subject: Re: [V2, 4/5] Documentation: dt-bindings: Document bindings for DW MIPI CSI-2 Host

Hi Luis,

Thank you for the patch.

On Thursday, 20 September 2018 14:16:42 EEST Luis Oliveira wrote:
> Add bindings for Synopsys DesignWare MIPI CSI-2 host.
> 
> Signed-off-by: Luis Oliveira <lolivei@...opsys.com>
> ---
> Changelog
> v2:
> - no changes
> 
>  .../devicetree/bindings/media/snps,dw-csi-plat.txt | 74 +++++++++++++++++++
>  1 file changed, 74 insertions(+)
>  create mode 100644
> Documentation/devicetree/bindings/media/snps,dw-csi-plat.txt
> 
> diff --git a/Documentation/devicetree/bindings/media/snps,dw-csi-plat.txt
> b/Documentation/devicetree/bindings/media/snps,dw-csi-plat.txt new file
> mode 100644
> index 0000000..028f5eb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/snps,dw-csi-plat.txt
> @@ -0,0 +1,74 @@
> +Synopsys DesignWare CSI-2 Host controller
> +
> +Description
> +-----------
> +
> +This HW block is used to receive image coming from an MIPI CSI-2 compatible
> +camera.
> +
> +Required properties:
> +- compatible: shall be "snps,dw-csi-plat"
> +- reg			: physical base address and size of the device memory mapped
> +  registers;
> +- interrupts		: CSI-2 Host interrupt
> +- snps,output-type	: Core output to be used (IPI-> 0 or IDI->1 or BOTH-
>2)
> These
> +			  values choose which of the Core outputs will be used, it
> +			  can be Image Data Interface or Image Pixel Interface.
> +- phys			: List of one PHY specifier (as defined in
> +			  Documentation/devicetree/bindings/phy/phy-bindings.txt).
> +			  This PHY is a MIPI DPHY working in RX mode.
> +- resets		: Reference to a reset controller (optional)
> +
> +Optional properties(if in IPI mode):
> +- snps,ipi-mode 	: Mode to be used when in IPI(Camera -> 0 or Controller -
>
> 1)
> +			  This property defines if the controller will use the video
> +			  timings available
> +			  in the video stream or if it will use pre-defined ones.

How does one select this ?

> +- snps,ipi-color-mode	: Bus depth to be used in IPI (48 bits -> 0 or 16
> bits -> 1)
> +			  This property defines the width of the IPI bus.

How about using the standard bus-width property in the endpoint of the output 
port ?

> +- snps,ipi-auto-flush	: Data auto-flush (1 -> Yes or 0 -> No). This
> property defines
> +			  if the data is automatically flushed in each vsync
> or if
> +			  this process is done manually

This seems like a configuration option, not a hardware property. I don't think 
it belongs to DT.

> +- snps,virtual-channel	: Virtual channel where data is present when in IPI
> mode. This
> +			  property chooses the virtual channel which IPI will use to
> +			  retrieve the video stream.

The virtual channel doesn't belong to DT, it should be queried from the sensor 
at runtime (and when a sensor can send multiple data streams, that should even 
be configurable).

> +The per-board settings:
> + - port sub-node describing a single endpoint connected to the camera as
> +   described in video-interfaces.txt[1].

You need to explicitly list all the ports for this device, with their number 
and function.

> +Example:
> +
> +	csi2_1: csi2@...0 {
> +		compatible = "snps,dw-csi-plat";
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		reg = < 0x03000 0x7FF>;
> +		interrupts = <2>;
> +		output-type = <2>;
> +		resets = <&dw_rst 1>;
> +		phys = <&mipi_dphy_rx1 0>;
> +		phy-names = "csi2-dphy";
> +
> +		/* IPI optional Configurations */
> +		snps,ipi-mode = <0>;
> +		snps,ipi-color-mode = <0>;
> +		snps,ipi-auto-flush = <1>;
> +		snps,virtual-channel = <0>;
> +
> +		/* CSI-2 per-board settings */
> +		port@1 {
> +			reg = <1>;
> +			csi1_ep1: endpoint {
> +				remote-endpoint = <&camera_1>;
> +				data-lanes = <1 2>;
> +			};
> +		};
> +		port@2 {
> +			csi1_ep2: endpoint {
> +				remote-endpoint = <&vif1_ep>;
> +			};
> +		};
> +	};
> +
> +

Extra blank lines.

-- 
Regards,

Laurent Pinchart