linux-kernel - Re: [PATCH v3] dt-bindings: media: adv748x: Document re-mappable addresses

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Date:   Mon, 13 Aug 2018 23:06:52 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Kieran Bingham <kieran.bingham@...asonboard.com>
Cc:     mchehab@...nel.org, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Hans Verkuil <hverkuil@...all.nl>, linux-media@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] dt-bindings: media: adv748x: Document re-mappable addresses

Hi Kieran,

Thank you for the patch.

On Thursday, 9 August 2018 22:29:44 EEST Kieran Bingham wrote:
> The ADV748x supports configurable slave addresses for its I2C pages.
> Document the page names, and provide an example for setting each of the
> pages explicitly.
> 
> Signed-off-by: Kieran Bingham <kieran.bingham@...asonboard.com>
> 
> ---
> v2:
>  - Fix commit message
>  - Extend documentation for the "required property" reg:
> 
> v3
>  - Fix missing comment from Laurent.
>  - correct the reg descrption
> ---
>  .../devicetree/bindings/media/i2c/adv748x.txt    | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/media/i2c/adv748x.txt
> b/Documentation/devicetree/bindings/media/i2c/adv748x.txt index
> 21ffb5ed8183..25a02496f4ba 100644
> --- a/Documentation/devicetree/bindings/media/i2c/adv748x.txt
> +++ b/Documentation/devicetree/bindings/media/i2c/adv748x.txt
> @@ -10,7 +10,11 @@ Required Properties:
>      - "adi,adv7481" for the ADV7481
>      - "adi,adv7482" for the ADV7482
> 
> -  - reg: I2C slave address
> +  - reg: I2C slave addresses
> +    The ADV748x has up to twelve 256-byte maps that can be accessed via the
> +    main I2C ports. Each map has it own I2C address and acts as a standard
> +    slave device on the I2C bus. The main address is mandatory, others are
> +    optional and remain at default values if not specified.
> 
>  Optional Properties:
> 
> @@ -18,6 +22,11 @@ Optional Properties:
>  		     "intrq3". All interrupts are optional. The "intrq3" interrupt
>  		     is only available on the adv7481
>    - interrupts: Specify the interrupt lines for the ADV748x
> +  - reg-names : Names of maps with programmable addresses.
> +		It shall contain all maps needing a non-default address.
> +		Possible map names are:
> +		  "main", "dpll", "cp", "hdmi", "edid", "repeater",
> +		  "infoframe", "cbus", "cec", "sdp", "txa", "txb"

Reading this again, the text doesn't document the "main" map very well. The 
main I2C address is always required, but if no other I2C address needs to be 
specified, the reg-names property can be omitted. Otherwise the "main" reg-
names entry is required.

This being said, this problem isn't specific to the adv748x bindings, so I 
don't want to block this patch until we figure out a proper wording that can 
be applied globally. For that reason,

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

>  The device node must contain one 'port' child node per device input and
> output port, in accordance with the video interface bindings defined in
> @@ -47,7 +56,10 @@ Example:
> 
>  	video-receiver@70 {
>  		compatible = "adi,adv7482";
> -		reg = <0x70>;
> +		reg = <0x70 0x71 0x72 0x73 0x74 0x75
> +		       0x60 0x61 0x62 0x63 0x64 0x65>;
> +		reg-names = "main", "dpll", "cp", "hdmi", "edid", "repeater",
> +			    "infoframe", "cbus", "cec", "sdp", "txa", "txb";
> 
>  		#address-cells = <1>;
>  		#size-cells = <0>;

-- 
Regards,

Laurent Pinchart