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@xxxxxxxx> > --- Acked-by: Stephen Boyd <sboyd@xxxxxxxxxx>
