linux-kernel - Re: [PATCH 1/4] Documentation/devicetree/bindings/video/bridge: megachips-stdpxxxx-ge-b850v3-fw

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Message-ID: <20170201155719.ng7otnioec7k6nvk@rob-hp-laptop>
Date:   Wed, 1 Feb 2017 09:57:19 -0600
From:   Rob Herring <robh@...nel.org>
To:     Peter Senna Tschudin <peter.senna@...labora.com>
Cc:     peter.senna@...il.com, airlied@...ux.ie, architt@...eaurora.org,
        akpm@...ux-foundation.org, daniel.vetter@...ll.ch,
        davem@...emloft.net, devicetree@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, enric.balletbo@...labora.com,
        eballetbo@...il.com, galak@...eaurora.org,
        gregkh@...uxfoundation.org, heiko@...ech.de,
        ijc+devicetree@...lion.org.uk, javier@...hile0.org, jslaby@...e.cz,
        kernel@...gutronix.de, linux-arm-kernel@...ts.infradead.org,
        linux@...linux.org.uk, linux-kernel@...r.kernel.org,
        linux@...ck-us.net, mark.rutland@....com, martin.donnelly@...com,
        martyn.welch@...labora.co.uk, mchehab@....samsung.com,
        pawel.moll@....com, p.zabel@...gutronix.de,
        thierry.reding@...il.com, rmk+kernel@...linux.org.uk,
        shawnguo@...nel.org, tiwai@...e.com, treding@...dia.com,
        ykk@...k-chips.com, laurent.pinchart@...asonboard.com,
        Fabio Estevam <fabio.estevam@....com>,
        Rask Ingemann Lambertsen <ccc94453@....cybercity.dk>
Subject: Re: [PATCH 1/4] Documentation/devicetree/bindings/video/bridge:
 megachips-stdpxxxx-ge-b850v3-fw

On Sat, Jan 28, 2017 at 03:21:30PM +0100, Peter Senna Tschudin wrote:
> Devicetree binding documentation for the second video output
> of the GE B850v3:
>    STDP4028-ge-b850v3-fw bridges (LVDS-DP)
>    STDP2690-ge-b850v3-fw bridges (DP-DP++)
> 
> Added entry for MegaChips at:
>  Documentation/devicetree/bindings/vendor-prefixes.txt

Your subject is so long I can't see anything useful. Begin with:

dt-bindings: display: ...

> 
> Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> Cc: Martyn Welch <martyn.welch@...labora.co.uk>
> Cc: Martin Donnelly <martin.donnelly@...com>
> Cc: Javier Martinez Canillas <javier@...hile0.org>
> Cc: Enric Balletbo i Serra <enric.balletbo@...labora.com>
> Cc: Philipp Zabel <p.zabel@...gutronix.de>
> Cc: Rob Herring <robh@...nel.org>
> Cc: Fabio Estevam <fabio.estevam@....com>
> Signed-off-by: Peter Senna Tschudin <peter.senna@...labora.com>
> ---
>  .../devicetree/bindings/vendor-prefixes.txt        |  1 +
>  .../bridge/megachips-stdpxxxx-ge-b850v3-fw.txt     | 92 ++++++++++++++++++++++
>  2 files changed, 93 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/video/bridge/megachips-stdpxxxx-ge-b850v3-fw.txt
> 
> diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
> index 1ef148d..b4c2f5c 100644
> --- a/Documentation/devicetree/bindings/vendor-prefixes.txt
> +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
> @@ -175,6 +175,7 @@ maxim	Maxim Integrated Products
>  mcube	mCube
>  meas	Measurement Specialties
>  mediatek	MediaTek Inc.
> +megachips	MegaChips
>  melexis	Melexis N.V.
>  melfas	MELFAS Inc.
>  memsic	MEMSIC Inc.
> diff --git a/Documentation/devicetree/bindings/video/bridge/megachips-stdpxxxx-ge-b850v3-fw.txt b/Documentation/devicetree/bindings/video/bridge/megachips-stdpxxxx-ge-b850v3-fw.txt
> new file mode 100644
> index 0000000..471db27
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/video/bridge/megachips-stdpxxxx-ge-b850v3-fw.txt

bindings/video/ is gone (though a few things snuck in). This goes in 
bindings/display/bridge/.

> @@ -0,0 +1,92 @@
> +Drivers for the second video output of the GE B850v3:
> +   STDP4028-ge-b850v3-fw bridges (LVDS-DP)
> +   STDP2690-ge-b850v3-fw bridges (DP-DP++)
> +
> +The video processing pipeline on the second output on the GE B850v3:
> +
> +   Host -> LVDS|--(STDP4028)--|DP -> DP|--(STDP2690)--|DP++ -> Video output
> +
> +Each bridge has a dedicated flash containing firmware for supporting the custom
> +design. The result is that, in this design, neither the STDP4028 nor the
> +STDP2690 behave as the stock bridges would. The compatible strings include the
> +suffix "-ge-b850v3-fw" to make it clear that the driver is for the bridges with
> +the firmware specific for the GE B850v3.
> +
> +The driver is powerless to control the video processing pipeline, as the two
> +bridges behaves as a single one. The driver is only needed for telling the host
> +about EDID / HPD, and for giving the host powers to ack interrupts.

Bindings describe h/w not drivers. Rephrase in terms of what control the 
h/w provides.

> +
> +Required properties:
> +  - compatible : should be "megachips,stdp4028-ge-b850v3-fw" or
> +    "megachips,stdp2690-ge-b850v3-fw".

Reformat with one per line.

> +  - reg : should contain the main address which is used to communicate with
> +    the bridge over i2c.

Just "reg : I2C bus address" is sufficient.

> +  - interrupt-parent : phandle of the interrupt controller that services
> +    interrupts to the device (stdp4028-ge-b850v3-fw)
> +  - interrupts : one interrupt should be described here, as in
> +    <0 IRQ_TYPE_LEVEL_HIGH> (stdp4028-ge-b850v3-fw)
> +  - ports : should describe the video signal connection between the host
> +    and the bridges.

You need to define how many ports and what each port is.

Rob