linux-kernel - Re: [PATCH v1 1/6] DT bindings: add bindings for ov965x camera module

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Message-ID: <d14b8c6e-b480-36f0-ed0a-684647617dbe@suse.de>
Date:   Fri, 23 Jun 2017 12:46:09 +0200
From:   Andreas Färber <afaerber@...e.de>
To:     "H. Nikolaus Schaller" <hns@...delico.com>
Cc:     Hugues Fruchet <hugues.fruchet@...com>,
        Mark Rutland <mark.rutland@....com>,
        devicetree <devicetree@...r.kernel.org>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Discussions about the Letux Kernel 
        <letux-kernel@...nphoenux.org>,
        Alexandre Torgue <alexandre.torgue@...com>,
        LKML <linux-kernel@...r.kernel.org>,
        Hans Verkuil <hverkuil@...all.nl>,
        Rob Herring <robh+dt@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Yannick Fertre <yannick.fertre@...com>,
        Sylwester Nawrocki <sylvester.nawrocki@...il.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Guennadi Liakhovetski <g.liakhovetski@....de>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-media@...r.kernel.org
Subject: Re: [PATCH v1 1/6] DT bindings: add bindings for ov965x camera module

Hi,

Am 23.06.2017 um 12:25 schrieb H. Nikolaus Schaller:
>> diff --git a/Documentation/devicetree/bindings/media/i2c/ov965x.txt b/Documentation/devicetree/bindings/media/i2c/ov965x.txt
>> new file mode 100644
>> index 0000000..0e0de1f
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/media/i2c/ov965x.txt
>> @@ -0,0 +1,37 @@
>> +* Omnivision OV9650/9652/9655 CMOS sensor
>> +
>> +The Omnivision OV965x sensor support multiple resolutions output, such as
>> +CIF, SVGA, UXGA. It also can support YUV422/420, RGB565/555 or raw RGB
>> +output format.
>> +
>> +Required Properties:
>> +- compatible: should be one of
>> +	"ovti,ov9650"
>> +	"ovti,ov9652"
>> +	"ovti,ov9655"
>> +- clocks: reference to the mclk input clock.
> 
> I wonder why you have removed the clock-frequency property?
> 
> In some situations the camera driver must be able to tell the clock source
> which frequency it wants to see.

That's what assigned-clock-rates property is for:

https://www.kernel.org/doc/Documentation/devicetree/bindings/clock/clock-bindings.txt

AFAIU clock-frequency on devices is deprecated and equivalent to having
a clocks property pointing to a fixed-clock, which is different from a
clock with varying rate.

Regards,
Andreas

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