On 06/23/2017 01:59 PM, H. Nikolaus Schaller wrote:
> Hi Suman,
>
>> Am 23.06.2017 um 20:05 schrieb Suman Anna <s-anna@xxxxxx>:
>>
>>>>>
>>>>> 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.
>>>
>>> I have seen it but it does not give me a good clue how to translate that into
>>> correct omap3isp node setup in a specific DT. Rather it raises more questions.
>>> Maybe because I don't understand completely what it is talking about.
>>>
>>> The fundamental question is if this "assigned-clock-rates" is already
>>> handled by ov965x->clk = devm_clk_get(&client->dev, NULL); ?
>>>
>>> Or should we define that for the omap3isp node?
>>>
>>> Then of course we need no new code and just use the right property names.
>>> And N900, N9 camera DTs should be updated.
>>
>> Look up of_clk_set_defaults() function in drivers/clk/clk-conf.c. This
>> function gets invoked usually during clock registration, and also gets
>> called in platform_drv_probe(), so the parents and clocks do get
>> configured before your driver gets probed. So, this provides a default
>> configuration if these properties are supplied (in either clock nodes or
>> actual device nodes), and if your driver needs to change the rates at
>> runtime, then you would have to do that in the driver itself.
>
> Ok, now I understand. Thanks!
>
> Quite hidden, but nice feature. I would never have thought that it exists.
> Especially as there are no examples around omap3isp cameras...
>
> And an fgrep assigned-clock-rates shows not many use cases outside CPU/SoC
> include files.
>
> But interestingly arch/arm/boot/dts/at91sam9g25ek.dts uses it for an ovti,ov2640 camera...
>
> So it seems that we just have to write:
>
> ov9655@30 {
> compatible = "ovti,ov9655";
> reg = <0x30>;
> clocks = <&isp 0>; /* cam_clka */
> assigned-clocks = <&isp 0>;
> assigned-clock-rates = <24000000>;
> };
Yeah, that looks alright and should work.
regards
Suman
>
> instead of introducing a new clock-frequency property and code to handle it.
>
> Or do I misinterpret what "parents" and "clocks" are in this context?
