Re: [PATCH v2 5/5] ARM: tegra: Add thermal reset (thermtrip) support to PMC

From: Mikko Perttunen
Date: Thu Aug 21 2014 - 09:12:00 EST


On 20/08/14 23:25, Stephen Warren wrote:
On 08/13/2014 06:41 AM, Mikko Perttunen wrote:
This adds a device tree controlled option to enable PMC-based
thermal reset in overheating situations. Thermtrip is supported on
Tegra30, Tegra114 and Tegra124. The thermal reset only works when
the thermal sensors are calibrated, so a soctherm driver is also
required.

If calibration is required, presumably the soctherm must initialize
before this thermtrip code can initialize, or this thermtrip logic might
be triggered by uncalibrated sensors?

SOCTHERM requires that each sensor be explicitly enabled before it gives readings. If a sensor is not enabled, the temperature given by the register (and used to trigger thermtrip) will be zero. So in order for a thermtrip shutdown to be caused before soctherm is initialized, the thermtrip temperature would have to be programmed to below zero (the default value is 105C), in which case an immediate shutdown would probably be in order anyway (unless the user uses LN2 or something to cool the soc below zero).


If so, then there needs to be some explicit mechanism to force the two
drivers into probing in the right order.

Because of the above, I think it isn't necessary to probe these in order.

Cheers,
Mikko
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