Den man. 22. feb. 2021 kl. 23.43 skrev Guenter Roeck <linux@xxxxxxxxxxxx>: > > On Thu, Feb 18, 2021 at 01:35:36PM +0100, Bruno Thomsen wrote: > > Hi, > > > > After updating the kernel from 5.8.17 to 5.11 systemd (246.6) is > > unable to init watchdog in pcf2127 during boot. Kernel option > > CONFIG_WATCHDOG_OPEN_TIMEOUT=300 is working as expected. > > It's possible to get watchdog from userspace working in > > the following 2 ways. > > 1) Disable watchdog in systemd and use busybox watchdog. > > 2) Restart systemd after boot with "kill 1". > > > > During boot setting the system clock from RTC is working. > > RTC read/write from userland with hwclock is also working. > > > > DTS: imx7d-flex-concentrator-mfg.dts > > SOC: NXP i.MX7D > > Drivers: rtc-pcf2127, spi-imx > > Communication: SPI > > > > There are no patches applied to the kernel. > > > > When systemd changes watchdog timeout it receives an > > error that to our best knowledge comes from spi-imx[1]. > > > > We suspect it's a race condition between drivers or > > incompatible error handling. > > > > Any help in investigating the issue is appreciated. > > > Difficult to say without access to hardware. The code does have a > potential problem, though: It calls pcf2127_wdt_ping not only from > watchdog code but also from various rtc related functions, but there > is not access protection. This is even more concerning because the ping > function is called from an interrupt handler. At the same time, the > watchdog initialization sets min_hw_heartbeat_ms to 500, which suggests > that there may be a minimum time between heartbeats (which is clearly > violated by the current code). Hi Guenter Thanks for input. You could be right about that, I don't think the watchdog feature should be available for use if the alarm feature is enabled due to how CTRL2 register behaves. The hardware I am testing on is a custom board, but it's actually possible to get a Raspberry Pi module called RasClock that has the chip. I will test some locking around WD_VAL register access as that is used in pcf2127_wdt_ping function. My initial test shows that spin_lock_irqsave around regmap calls are not a good idea as it result in: BUG: scheduling while atomic: watchdog/70/0x00000002 BUG: scheduling while atomic: systemd/1/0x00000002 /Bruno
