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Subject: [rtc-linux] Re: [PATCH] rtc: sunxi: use external oscillator
To: Chen-Yu Tsai <wens@csie.org>
References: <577CC494.8020103@roslen.de> <20160706202000.GC4247@lukather>
 <577DDF8C.6060404@roslen.de>
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Cc: Maxime Ripard <maxime.ripard@free-electrons.com>,
 Alessandro Zummo <a.zummo@towertech.it>,
 Alexandre Belloni <alexandre.belloni@free-electrons.com>,
 rtc-linux@googlegroups.com
From: Stephan Roslen <stephan@roslen.de>
Message-ID: <577DF2B9.602@roslen.de>
Date: Thu, 7 Jul 2016 08:12:09 +0200
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On 07.07.2016 06:53, Chen-Yu Tsai wrote:
> On Thu, Jul 7, 2016 at 12:50 PM, Stephan Roslen <stephan@roslen.de> wrote:
>> I agree. Checking the diagram in subsection 1.5.2 of the A20 manual it seems, that LOSC can be a source for clocks like CPU and some SoC busses. So my patch could indeed mess with the whole clock tree.
> 
> (Please wrap your email)

Sorry.

> 
> Within the current sunxi clk structure, the LOSC is registered as a fixed
> 32.768 KHz clk. So this patch actually makes things right.

In this case it should still be addressed somewhere in drivers/clk/sunxi, not 
in drivers/rtc, I guess? Would you prefer setting the external 32.768 KHz crystal
as hard coded default instead of providing the muxer? It could be considered okay,
for the data sheet seems to demand presence of the external oscillator and there
is absolutely no use in a 32KHz +- 20% oscillator, if a 32.768KHz crystal is
available.

Stephan

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