Hi, On Mon, 5 Aug 2019 at 13:10, Ondřej Jirman <megous@xxxxxxxxxx> wrote: > > On Mon, Aug 05, 2019 at 06:54:17PM +0800, Chen-Yu Tsai wrote: > > On Mon, Aug 5, 2019 at 6:45 PM Ondřej Jirman <megous@xxxxxxxxxx> wrote: > > > [snip] > > Interesting. :) I have the BSP I was using saved here: > > https://megous.com/git/linux/tree/drivers/rtc/rtc-sunxi.c?h=h6-4.9-bsp#n649 > > It's based of 4.9.119 > > https://megous.com/git/linux/log/?h=h6-4.9-bsp > > I don't remember where I found it. But I imported it fairly recently, and > the code you pointed to looks like an older version that I can found in some > beta H6 BSP, that I imported way earlier and is based on 4.9.56: The last recent that I know is from OrangePi H6 but it's based on 4.9.118. https://github.com/orangepi-xunlong/OrangePiH6_Linux4_9 Regards, Clément > > https://megous.com/git/linux/tree/drivers/rtc/rtc-sunxi.c?h=linux-h6 > https://megous.com/git/linux/log/?h=linux-h6 > > Hmm, archeology. :) > > > > For older BSPs, the init sequence looked like this: > > > > > > 482 /* > > > 483 * Step1: select RTC clock source > > > 484 */ > > > 485 tmp_data = sunxi_rtc_read(SUNXI_LOSC_CTRL_REG); > > > 486 tmp_data &= (~REG_CLK32K_AUTO_SWT_EN); > > > 487 tmp_data |= (RTC_SOURCE_EXTERNAL | REG_LOSCCTRL_MAGIC); > > > 488 tmp_data |= (EXT_LOSC_GSM); > > > 489 sunxi_rtc_write(tmp_data, SUNXI_LOSC_CTRL_REG); > > > 490 > > > > > > EXT_LOSC_GSM has values 4 values from low to high, and I guess it configures > > > gain for the oscillator's amplifier in the feedback loop of the circuit. > > > > > > So the new code, for some reason changed from single write to sequence > > > of individual writes/config steps: > > > > > > 1) disable auto-switch and enable auto-switch bypass > > > 2) select RTC clock source (to LOSC) > > > (wait) > > > > Maybe it's possible to glitch if these two are combined? > > That's what I thought too. Or the programmer thought so, and was just > programming defensively, and there's no real problem in the practice. > > But that specific delay() seems like someone trying to solve a real issue. Of > course there's no knowing if it was on H6 or on some other SoC. > > regards, > o. > > > > > > 3) configure gain on the LOSC > > > > > > regards, > > > o. > > > > > > > ChenYu > > > > > > -- > > > You received this message because you are subscribed to the Google Groups "linux-sunxi" group. > > > To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscribe@xxxxxxxxxxxxxxxx. > > > To view this discussion on the web, visit https://groups.google.com/d/msgid/linux-sunxi/20190805104529.z3mex3m2tss7lzlr%40core.my.home. > > -- > You received this message because you are subscribed to the Google Groups "linux-sunxi" group. > To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscribe@xxxxxxxxxxxxxxxx. > To view this discussion on the web, visit https://groups.google.com/d/msgid/linux-sunxi/20190805111037.76vmanzcurffpbdf%40core.my.home.
