Am 23.06.2017 um 16:53 schrieb H. Nikolaus Schaller: > Hi Laurent, > >> Am 23.06.2017 um 13:58 schrieb Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>: >> >> Hi Nikolaus, >> >> On Friday 23 Jun 2017 12:59:24 H. Nikolaus Schaller wrote: >>> Am 23.06.2017 um 12:46 schrieb Andreas Färber <afaerber@xxxxxxx>: >>>> 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? Please read the documentation link I sent - it's in the very bottom and should have an example. Regards, Andreas -- SUSE Linux GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany GF: Felix Imendörffer, Jane Smithard, Graham Norton HRB 21284 (AG Nürnberg)
