Dne sobota, 24. avgust 2019 ob 23:27:46 CEST je Ondřej Jirman napisal(a): > Hello Jernej, > > On Sat, Aug 24, 2019 at 11:09:49PM +0200, Jernej Škrabec wrote: > > > Visually? > > > > > > That would explain why it doesn't work for you. The mainline RTC driver > > > disables auto-switch feature, and if your board doesn't have a crystal > > > for > > > LOSC, RTC will not generate a clock for the RTC. > > > > > > H6's dtsi describes by default a situatiuon with external 32k crystal > > > oscillator. See ext_osc32k node. That's incorrect for your board if it > > > doesn't have the crystal. You need to fix this in the DTS for your board > > > instead of patching the driver. > > > > I see that reparenting is supported, but I'm not sure how to fix that in > > DT. Any suggestion? > > You may try removing the clocks property from rtc node. I don't think this would work: https://elixir.bootlin.com/linux/latest/source/drivers/rtc/rtc-sun6i.c#L246 > > > > The driver has parent clock selection logic in case the LOSC crystal is > > > not > > > used. > > > > > > Your patch enables automatic detection of LOSC failure and RTC changes > > > clock to LOSC automatically, despite what's described in the DTS. That > > > may fix the issue, but is not the correct solution. > > > > > > Registers on my board look like this (external 32k osc is used) for > > > reference: > > > > > > LOSC_CTRL_REG[7000000]: 8011 > > > > > > KEY_FIELD ??? (0) > > > LOSC_AUTO_SWT_BYPASS EN (1) > > > LOSC_AUTO_SWT_EN DIS (0) > > > EXT_LOSC_EN EN (1) > > > EXT_LOSC_GSM LOW (0) > > > BATTERY_DIR DISCHARGE (0) > > > LOSC_SRC_SEL EXT32k (1) > > > > > > LOSC_AUTO_SWT_STA_REG[7000004]: 1 > > > > > > EXT_LOSC_STA OK (0) > > > LOSC_AUTO_SWT_PEND NOEFF (0) > > > LOSC_SRC_SEL_STA EXT32K (1) > > > > In my case LOSC_CTRL_REG has value 0x4010 and LOSC_AUTO_SWT_STA_REG > > has value 0x4, so there is issue with external crystal (it's missing) and > > RTC switched to internal one. > > > > BTW, what's wrong with automatic switching? Why is it disabled? > > It always was disabled on mainline (bit 14 was set to 0 even before my > patch). H6 just probably has another extra undocummented bit, that's needed > to disables it properly. > > You probably don't want a glitch to switch your RTC from high-precision > clock to a low precision one possibly without any indication in the > userspace or a kernel log. > > Regardless of all this, DTS needs to have a correct description of the HW, > which means if RTC module is not connected to the 32.757kHz crystal/clock, > clocks property should be empty. If we are talking about correct HW description, then clock property should actually have possibility that two clocks are defined - one for internal RC (always present) and one external crystal (optional). In such case I could really just omit external clock and be done with it. But I'm not sure if such solution is acceptable at this point. Best regards, Jernej > > regards, > o. > > > Best regards, > > Jernej > > > > > regards, > > > > > > o. > > > > > > > > The real issue probably is that the mainline driver is missing this: > > > > > > > > > > https://megous.com/git/linux/tree/drivers/rtc/rtc-sunxi.c?h=h6-4.9-b > > > > > sp#n > > > > > 650 > > > > > > > > Not sure what you mean by that. ext vs. int source selection? > > > > > > > > > > > > > > > > Best regards, > > > > Jernej > > > > > > > > > regards, > > > > > > > > > > o.
