# Re: \[PATCH v3 4/7\] thermal/drivers/tegra: Add driver for Tegra30 thermal sensor

- From: Viresh Kumar \<viresh.kumar@linaro.org\>
- Date: 2021-06-15 10:26:40 
- List: linux-devicetree
- Page: https://ratatoskr.run/linux-devicetree/2021/06/1414607
- Thread: https://ratatoskr.run/linux-devicetree/2021/05/1395821/t.md

```text
On 15-06-21, 12:03, Daniel Lezcano wrote:
> 
> [Cc Viresh]
> 
> On 29/05/2021 19:09, Dmitry Osipenko wrote:
> > All NVIDIA Tegra30 SoCs have a two-channel on-chip sensor unit which
> > monitors temperature and voltage of the SoC. Sensors control CPU frequency
> > throttling, which is activated by hardware once preprogrammed temperature
> > level is breached, they also send signal to Power Management controller to
> > perform emergency shutdown on a critical overheat of the SoC die. Add
> > driver for the Tegra30 TSENSOR module, exposing it as a thermal sensor
> > and a cooling device.
> 
> IMO it does not make sense to expose the hardware throttling mechanism
> as a cooling device because it is not usable anywhere from the thermal
> framework.
> 
> Moreover, that will collide with the thermal / cpufreq framework
> mitigation (hardware sets the frequency but the software thinks the freq
> is different), right ?

I am not even sure what the cooling device is doing here:

tegra_tsensor_set_cur_state() is not implemented and it says hardware
changed it by itself. What is the benefit you are getting out of the
cooling device here ?

> The hardware limiter should let know the cpufreq framework about the
> frequency change.
> 
> 	https://lkml.org/lkml/2021/6/8/1792
> 
> May be post the sensor without the hw limiter for now and address that
> in a separate series ?

-- 
viresh
```