Hi Vaibhav,
On 11/12/2012 11:38 AM, Hiremath, Vaibhav wrote:
> On Fri, Nov 09, 2012 at 00:46:28, Hunter, Jon wrote:
>>
>> On 11/08/2012 12:59 PM, Hiremath, Vaibhav wrote:
>>> On Fri, Nov 09, 2012 at 00:24:23, Hunter, Jon wrote:
>>>>
>>>> On 11/08/2012 01:59 AM, Igor Grinberg wrote:
>>>>
>>>> [snip]
>>>>
>>>>> There is no reliable way to determine which source should be used in runtime
>>>>> for boards that do not have the 32k oscillator wired.
>>>>
>>>> So thinking about this some more and given that we are moving away from
>>>> board files, if a board does not provide a 32kHz clock source, then this
>>>> should be reflected in the device-tree source file for that board.
>>>> Hence, at boot time we should be able to determine if a 32kHz clock
>>>> source can be used.
>>>>
>>>
>>> Let me feed some more thoughts here :)
>>>
>>> The way it is being detected currently is based on timer idle status bit.
>>> I am worried that, this is the only option we have.
>>
>> Why not use device-tree to indicate the presence of a 32k clock source?
>> This seems like a board level configuration and so device-tree seems to
>> be the perfect place for this IMO.
>>
>
> I think I agree with you, but for this to happen in clean way, its time to
> start populating clock-nodes in DT, don't you think? Something like,
>
>
> clocks {
> rtc_clk: clk@X {
> compatible = "crystal-32k, per-32k, xyz";
> clock-frequency = <32768>;
> };
> ...
> };
>
> Timer {
>
> ref-clock = <&rtc_clk>;
> };
>
> What do you think?
That's indeed the proper way to do it, since this is a pure board level
parameter and we do have the binding to express that.
We just have to add that in the DTS:-)
Regards,
Benoit
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