RTC0 invalid - rtc0: read_time: rtc_time isn't valid - PCF2129 on LX2160A COM

NXP LX2160
1

I am trying to use a bit newer kernel than the 5.10.x and vanilla/mainline is highly preferred. After some initial struggle, it’s running pretty all right, there are just a few problems left.

One is that RTC driver has stopped working properly. There should be PCF2129AT on i2c-2, address 0x51. I used CONFIG_RTC_DRV_PCF2127=y in Linux kernel (tried 5.15.33, 5.15.46, 5.18.3). I get the same result:

rtc-pcf2127-i2c 2-0051: pcf2127_rtc_read_time: raw data is cr3=5a, sec=14, min=14, hr=14, mday=14, wday=14, mon=14, year=14
rtc-pcf2127-i2c 2-0051: pcf2127_rtc_read_time: tm is secs=14, mins=14, hours=14, mday=14, mon=13, year=114, wday=4
rtc rtc0: read_time: rtc_time isn’t valid

Other i2c devices like MUX, SFP I2C access or amc6821 seems to work properly.
Is there a dependency for the RTC0 or anything I am missing?
(There is also a RTC1 present on the board, but it’s not useful for battery backed-up real time storage, only for alarms, this also seems to work properly.)

2

Have you tried setting the time to be correct with the hwclock command? The state of the RTC can be inconsistent until it is set the first time.

3

Of course. I waited to have sync over ntp and used hwclock --systohc. It didn’t seem to produce any error, but any try to use hwclock to read couses errors mentioned above.