Re: [PATCH v1 6/7] arm64: dts: sdm845: Increase alert trip point to 95 degrees

[Amit Kucheria]

On Thu, Jan 10, 2019 at 5:59 AM Stephen Boyd <swboyd@xxxxxxxxxxxx> wrote:
>
> Quoting Amit Kucheria (2019-01-09 16:00:55)
> > 75 degrees is too aggressive for throttling the CPU. After speaking to
> > Qualcomm engineers, increase it to 95 degrees.
> >
> > Signed-off-by: Amit Kucheria <amit.kucheria@xxxxxxxxxx>
> > ---
> >  arch/arm64/boot/dts/qcom/sdm845.dtsi | 16 ++++++++--------
>
> Is the plan that these are some defaults that would be adjusted by board
> variants? Just curious why we have anything in here and don't punt it
> all to each board dts file.

These values are meant to be safe values for silicon operation as
characterised[1] by the HW team. So I'd consider them a more than just
default values. It also gives future boards a safe starting point.

IMHO it would be better to have the characterized values merged
upstream and if really required, those values can be tweaked in the
board-specific DTS.

[1] Caveat: The characterisation probably focused on mobile devices
and might change depending on form-factor, active cooling and heat
dissipation design but those differences should only impact the skin
temperature, not the operation of the SoC itself.