Re: [PATCH v8 01/29] thermal/core: Add a generic thermal_zone_get_trip() function

On Mon, Mar 13, 2023 at 11:45:41AM +0100, Daniel Lezcano wrote:

Thanks for reporting this, I think the fix you are proposing is correct
regarding the previous behavior.

However, I disagree with the commit 81ad4276b505, because it defines the
zero as an invalid trip point. But some platforms have warming devices, when
the temperature is too cold, eg 0°C, we enable the warming device in order
to stay in the functioning temperature range.

Other devices can do the same with negative temperature values.

This feature is not yet upstream and the rework of the trip point should
allow proper handling of cold trip points.

If you can send the change to fix the regression that would be great.

Thanks for the reply. Will send you the fix later this week. I want to
test it across all of our systems.

But keep in mind, the driver is assuming an internal thermal framework
behavior. The trips_disabled is only to overcome a trip point description
bug and you should not rely on it as well as not changing the trip points on
the fly after they are registered.

Actually, the mlxsw driver should just build a valid array of trip points
without 0°C trip point and pass it to
thermal_zone_device_register_with_trips(). That would be a proper change
without relying on a side effect of the thermal trip bug 0°C workaround.

Understood. Will check with Vadim what we can do in order not to rely on
this behavior.