Re: [PATCH 3/8] rtc: omap: Add external clock enabling support

[Grygorii Strashko <grygorii.strashko-l0cyMroinI0@public.gmane.org>]

Hi Alexandre,
On 08/05/2015 02:43 PM, Alexandre Belloni wrote:
> On 05/08/2015 at 13:41:19 +0200, Alexandre Belloni wrote :
>> Hi,
>>
>> On 05/08/2015 at 04:13:17 -0700, Tony Lindgren wrote :
>>> * Keerthy <j-keerthy-l0cyMroinI0@public.gmane.org> [150805 03:53]:
>>>> Based on the board property switch the source from internal
>>>> to external clock. Switching to external source is needed for
>>>> rtcwake to work in low power modes.
>>>
>>> I think this is better handled based on the compatible string
>>> in the device driver rather than introducing a custom dts
>>> property for it. You can just set the quirk flag in the driver
>>> probe based on the compatible.
>>>
>>
>> Why not use the clocks property? Then you can pass an external clock. If
>> it is present you can even get its rate if this is needed at some point
>> in the future. You could also disable it when going to suspend.
>>
> 
> Actually, that was already my suggestion back in april:
> http://patchwork.ozlabs.org/patch/445631/
> 
> (Please Cc: the rtc mailing list for RTC related patches so that they
> get picked up by patchwork).
> 

Pls, correct me if I'm not right. Is below what you propose?

Doard dts:
/ {
 rtc_32k_ext_clk: rtc_osc_xi_clkin32_ext {
	#clock-cells = <0>;
	compatible = "fixed-clock";
	clock-frequency = <32000>;
  	clock-output-names = "rtc_osc_xi_clkin32";
  };
}

 &rtc {
 	status = "okay";
	clocks = <&sys_32k_ck>, <&rtc_32k_ext_clk>;
	[optional] clock-names = "int-clk", "ext-clk";
 };

Driver:
1) clk0 is mandatory, internal clock source
2) clk1 is optional, external clock source, so
if present - RTC driver can switch to use ext clock source

-- 
regards,
-grygorii
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