Re: [PATCH 09/15] clk: sunxi-ng: r40: Force LOSC parent to RTC LOSC output

Stephen Boyd
2018-11-28T21:29:07Z

Quoting Chen-Yu Tsai (2018-11-28 01:30:07)
> On the R40, in addition to a mux between the RTC's own RC oscillator and
> an external 32768 Hz crystal, which are muxed inside the RTC module, the
> CCU also has its own RC oscillator, which runs at around 2 MHz, and can
> be muxed with the LOSC output from the RTC. This muxed output is called
> "SYS 32K" in the module clock diagram, but otherwise referred to as the
> LOSC throughout the CCU documentation.
>
> The RC oscillator is not very accurate, even though it has an undocumented
> calibration function. We really want a precise clock at 32768 Hz,
> instead of something at around 32 KHz. This patch forces the SYS 32K
> clock to use the RTC output as its parent, and doesn't bother
> registering the internal oscillator nor a clock mux.
>
> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
> ---

Acked-by: Stephen Boyd <sboyd@kernel.org>