Re: [PATCH] arm64: dts: qcom: shikra: Drop CPU critical trips

[Gaurav Kohli]

On 10/15/2026 4:43 PM, Konrad Dybcio wrote:
> On 9/25/26 12:24 PM, Gaurav Kohli wrote:
> > On 9/25/2026 3:13 PM, Abel Vesa wrote:
> > > On 26-09-24 19:52:32, Gaurav Kohli wrote:
> > > > Shikra firmware handles CPU thermal mitigation up to 117 C, while
> > > > Linux CPU critical trips trigger at 115 C. This can shut the system
> > > > down before firmware reaches the end of its mitigation range.
> > > >
> > > > Drop the critical trips from the CPU thermal zones and leave the hot
> > > > trips, non-CPU critical trips and GPUSS passive cooling map unchanged.
> > >
> > > I thought that was the whole point of having the critical trips set to
> > > 115 C, so that the kernel can gracefully shut down before firmware cuts
> > > it off.
> > >
> > > What happens if CPU gets to 117 C and the critical trips are removed?
> > > How will firmware thermal mitigation handle it?
> >
> > Thanks Abel for review.
> >
> > For the CPU thermal zones on this SoC, hardware-side mitigation is already available at 115 C and 117 C, and hardware shutdown is at 120 C. Because of that, a Linux critical trip at 115 C is not very useful. It overlaps with the hardware mitigation range and can trigger shutdown before the firmware thermal sequence has completed.
>
> Does the hardware mitigation just pull the plug, or does it signal
> to the OS that it's about to? We absolutely need the OS to be aware,
> so that e.g. the filesystem will be synced.

Thanks Konrad for the review.

The OS is not notified before the final HW shutdown at 120 C. There is 
also no useful margin for a Linux critical trip here, firmware/HW 
mitigation starts at 115/117 C and hw shutdown is at 120.

So 115 C overlaps with firmware mitigation, while placing it higher is
too close to HW shutdown to be useful.

> Konrad
>
> > So the CPU critical trips are removed and the firmware/hardware mitigation is left to handle those thresholds as critical is not helping here.