[rtc-linux] Re: [PATCH] rtc: sunxi: use external oscillator

On 07.07.2016 06:50, Stephan Roslen wrote:

On 06.07.2016 22:20, Maxime Ripard wrote:

quoted

The issue is actually worse than that.

That register controls the losc source for the whole clock tree, so it
will affect every clock in the system.

In order to have that correctly propagated, you should register a new
mux here in the clock framework, and have all the other clocks using
that mux as a parent.

=20
I agree. Checking the diagram in subsection 1.5.2 of the A20 manual it se=

ems, 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.

Sorry for the addition. The mess of course is not that huge, for the mux se=
lects between a 32KHz Oscillator with +- 20% tolerance, thus ranging from 2=
5.6 to 38.4 KHz and the 32.768KHz external oscillator. Hence muxing to 32.7=
68KHz should be no problem for any clk, that was fine with the internal osc=
illator as clk source. Though still you're absolutely right, that this shou=
ld be handled in code correctly.

Stephan

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