Hi Laurent, > Am 23.06.2017 um 13:58 schrieb Laurent Pinchart > <laurent.pinch...@ideasonboard.com>: > > Hi Nikolaus, > > On Friday 23 Jun 2017 12:59:24 H. Nikolaus Schaller wrote: >> Am 23.06.2017 um 12:46 schrieb Andreas Färber <afaer...@suse.de>: >>> 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-b >>> indings.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. >> >> I am not sure if that helps here. The OMAP3-ISP does not have a fixed clock >> rate so we can only have the driver define what it wants to see. >> >> And common practise for OMAP3-ISP based camera modules (e.g. N900, N9) is >> that they do it in the driver. >> >> Maybe ISP developers can comment? > > The OMAP3 ISP is a variable-frequency clock provider. The clock frequency is > controlled by the clock consumer. As such, it's up to the consumer to decide > whether to compute and request the clock rate dynamically at runtime, or use > the assigned-clock-rates property in DT. > > Some ISPs include a clock generator, others don't. It should make no > difference whether the clock is provided by the ISP, by a dedicated clock > source in the SoC or by a discrete on-board adjustable clock source.
Thanks for explaining the background. Do you have an hint or example how to use the assigned-clock-rates property in a DT for a camera module connected to the omap3isp? Or does it just mean that it defines the property name? BR, Nikolaus
