Messages in this thread | | | Date | Mon, 21 Feb 2022 15:49:16 +0000 | Subject | Re: [PATCH v3 2/4] hwmon: (lm90) Use hwmon_notify_event() | From | Jon Hunter <> |
| |
On 21/02/2022 15:43, Guenter Roeck wrote:
...
>> We observed a random null pointer deference crash somewhere in the >> thermal core (crash log below is not very helpful) when calling >> mutex_lock(). It looks like we get an interrupt when this crash >> happens. >> >> Looking at the lm90 driver, per the above, I now see we are calling >> hwmon_notify_event() from the lm90 interrupt handler. Looking at >> hwmon_notify_event() I see that ... >> >> hwmon_notify_event() >> --> hwmon_thermal_notify() >> --> thermal_zone_device_update() >> --> update_temperature() >> --> mutex_lock() >> >> So although I don't completely understand the crash, it does seem >> that we should not be calling hwmon_notify_event() from the >> interrupt handler. >> > As mentioned separately, this is not the problem.
Yes I can see that now.
> I think the problem may be that this is not a devicetree system > (or the lm90 devide does not have a devicetree node), but thermal > notification currently only works in such systems because the hwmon > subsystem uses the devicetree registration method. At the same time, > CONFIG_THERMAL_OF is obviously enabled. Unfortunately, the hwmon code > does not bail out in that situation due to another bug.
The platform I see this on does use device-tree and it does have a node for the ti,tmp451 device which uses the lm90 device. This platform uses the device-tree source arch/arm64/boot/dts/nvidia/tegra194-p2972-0000.dts and the tmp451 node is in arch/arm64/boot/dts/nvidia/tegra194-p2888.dtsi.
Cheers Jon
-- nvpublic
| |