linux-kernel - Re: [V3, 3/4] Documentation: dt-bindings: media: Document bindings for DW MIPI CSI-2 Host

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Date:   Wed, 14 Nov 2018 22:16:01 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Luis de Oliveira <luis.oliveira@...opsys.com>
Cc:     Rob Herring <robh@...nel.org>, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org, joao.pinto@...opsys.com,
        festevam@...il.com, Mauro Carvalho Chehab <mchehab@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        Arnd Bergmann <arnd@...db.de>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Neil Armstrong <narmstrong@...libre.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Keiichi Watanabe <keiichiw@...omium.org>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Todor Tomov <todor.tomov@...aro.org>,
        devicetree@...r.kernel.org
Subject: Re: [V3, 3/4] Documentation: dt-bindings: media: Document bindings for DW MIPI CSI-2 Host

Hi Luis,

Thank you for the patch.

On Tuesday, 13 November 2018 12:00:22 EET Luis de Oliveira wrote:
> On 24-Oct-18 18:40, Rob Herring wrote:
> > On Fri, Oct 19, 2018 at 02:52:25PM +0200, Luis Oliveira wrote:
> >> Add bindings for Synopsys DesignWare MIPI CSI-2 host.
> >> 
> >> Signed-off-by: Luis Oliveira <lolivei@...opsys.com>
> >> ---
> >> Changelog
> >> v2-V3
> >> - removed IPI settings
> >> 
> >>  .../devicetree/bindings/media/snps,dw-csi-plat.txt | 52 ++++++++++++++++
> >>  1 file changed, 52 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..be3da05
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/media/snps,dw-csi-plat.txt
> >> @@ -0,0 +1,52 @@
> >> +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"
> > 
> > 'plat' is really part of the name of the h/w block?
> 
> It is the name of the platform driver for CSI compatible with this block. Is
> that wrong?

DT bindings describe hardware, not drivers. This should be the name of the IP 
core, regardless of how the drivers are architectured and named.

> >> +- 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.

Does this describe what outputs the IP core has been instantiated 
(synthesized) with, or what output(s) are used at runtime ? How does that 
relate to the port nodes ?

> >> +- 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)
> >> +
> >> +The per-board settings:
> >> + - port sub-node describing a single endpoint connected to the camera as
> >> +   described in video-interfaces.txt[1].
> > 
> > Need to say 2 ports and what is each port? Why no port #0?
> 
> I will elaborate on that.
> 
> >> +
> >> +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";
> > 
> > Not documented. Not really needed for a single entry, so I'd just drop
> > it.
> 
> I will, thanks.
> 
> >> +
> >> +		/* 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>;
> >> +			};
> >> +		};
> >> +	};

-- 
Regards,

Laurent Pinchart