Re: watchdog: pcf2127: systemd fails on 5.11

Hi,

On 24/02/2021 15:55:00+0100, Bruno Thomsen wrote:

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 have an eval board for the PCF2127 (and PCF2129), the OM13513.

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

The issue is not only regmap but the fact that i2C and spi accesses are
allowed to sleep.


-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com