linux-kernel - Re: [PATCH] dt-bindings: media: i2c: Fix external clock frequency for OV5645

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Message-ID: <20181114105712.j5jkspfasujiyqzs@valkosipuli.retiisi.org.uk>
Date:   Wed, 14 Nov 2018 12:57:12 +0200
From:   Sakari Ailus <sakari.ailus@....fi>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     mchehab@...nel.org, robh+dt@...nel.org, todor.tomov@...aro.org,
        hansverk@...co.com, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dt-bindings: media: i2c: Fix external clock frequency
 for OV5645

Hi Manivannan,

On Wed, Nov 14, 2018 at 04:09:35PM +0530, Manivannan Sadhasivam wrote:
> Commit "4adb0a0432f4 media: ov5645: Supported external clock is 24MHz"
> modified the external clock frequency to be 24MHz instead of the
> 23.88MHz in driver. Hence, make the same change in corresponding bindings
> doc and mention the acceptable tolerance.
> 
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
>  Documentation/devicetree/bindings/media/i2c/ov5645.txt | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/media/i2c/ov5645.txt b/Documentation/devicetree/bindings/media/i2c/ov5645.txt
> index fd7aec9f8e24..b155583469a4 100644
> --- a/Documentation/devicetree/bindings/media/i2c/ov5645.txt
> +++ b/Documentation/devicetree/bindings/media/i2c/ov5645.txt
> @@ -8,7 +8,8 @@ Required Properties:
>  - compatible: Value should be "ovti,ov5645".
>  - clocks: Reference to the xclk clock.
>  - clock-names: Should be "xclk".
> -- clock-frequency: Frequency of the xclk clock.
> +- clock-frequency: Frequency of the xclk clock. Should be 24MHz with 1%
> +                   acceptable tolerance.

DT bindings are for documenting the hardware, not the driver implementation.
The sensor supports a range AFAIU, not a specific frequency.

The bit below seems good.

>  - enable-gpios: Chip enable GPIO. Polarity is GPIO_ACTIVE_HIGH. This corresponds
>    to the hardware pin PWDNB which is physically active low.
>  - reset-gpios: Chip reset GPIO. Polarity is GPIO_ACTIVE_LOW. This corresponds to
> @@ -37,7 +38,7 @@ Example:
>  
>  			clocks = <&clks 200>;
>  			clock-names = "xclk";
> -			clock-frequency = <23880000>;
> +			clock-frequency = <24000000>;
>  
>  			vdddo-supply = <&camera_dovdd_1v8>;
>  			vdda-supply = <&camera_avdd_2v8>;
> -- 
> 2.17.1
> 

-- 
Sakari Ailus
e-mail: sakari.ailus@....fi