[PATCH] hwmon: (dell-smm-hwmon) Disable BIOS fan control upon loading

[Giovanni Mascellani]

Hi,

Il 13/11/19 09:15, Ilie Halip ha scritto:
> The module parameter value, when specified, should be used.
> When it is not specified, you probably still want to check the
> dmi_table.

Hmm, that does not solve the problem mentioned by Valdis: if there is no
userspace daemon piloting the fan, the module should not do anything, so
that the BIOS still has a chance to regulate the fan (which might not
mean much: the BIOS seems to be very buggy, and sometimes it won't speed
up the fan even when all the cores are busy compiling C++ for minutes
and very hot; but at least that's not the kernel module's fault).

Maybe another approach is to only disable the BIOS code when the first
SET_FAN command is received, so I know that there is someone in
userspace. Of course I am not protected from the possibility that the
userspace daemon sends wrong commands or crashes, but I am not protected
anyway. I rely on other lower level measures (such as, the CPU powering
down then it crosses a critical threshold) to protect the hardware from
this scenario.

Is this a reasonable solution?

> Coincidentally, I have a Dell laptop model which might be
> affected by a similar issue. I'd be happy to test your patch.

That would be good!

Thanks, Giovanni.
-- 
Giovanni Mascellani <g.mascellani at gmail.com>
Postdoc researcher - Université Libre de Bruxelles

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