On Mon, Mar 20, 2023 at 02:45:15PM +0300, Paul Fertser wrote:
> Hello,
>
> We are seeing wrong DTS temperatures on at least "Intel(R) Xeon(R)
> Bronze 3204 CPU @ 1.90GHz" and most probably other Skylake Xeon CPUs
> are also affected, see inline.
Thanks for the report! I guess we need a fix for this indeed.
> On Tue, Feb 08, 2022 at 04:36:36PM +0100, Iwona Winiarska wrote:
> > Add peci-cputemp driver for Digital Thermal Sensor (DTS) thermal
> > readings of the processor package and processor cores that are
> > accessible via the PECI interface.
> ...
> > +static const struct cpu_info cpu_hsx = {
> > + .reg = &resolved_cores_reg_hsx,
> > + .min_peci_revision = 0x33,
> > + .thermal_margin_to_millidegree = &dts_eight_dot_eight_to_millidegree,
> > +};
> > +
> > +static const struct cpu_info cpu_icx = {
> > + .reg = &resolved_cores_reg_icx,
> > + .min_peci_revision = 0x40,
> > + .thermal_margin_to_millidegree = &dts_ten_dot_six_to_millidegree,
> > +};
> ...
> > + {
> > + .name = "peci_cpu.cputemp.skx",
> > + .driver_data = (kernel_ulong_t)&cpu_hsx,
> > + },
>
> With this configuration we get this data:
>
> /sys/bus/peci/devices/0-30/peci_cpu.cputemp.skx.48/hwmon/hwmon15# grep . temp[123]_{label,input}
> temp1_label:Die
> temp2_label:DTS
> temp3_label:Tcontrol
> temp1_input:30938
> temp2_input:67735
> temp3_input:80000
>
> On the host system "sensors" report
>
> Package id 0: +31.C (high = +80.C, crit = +90.C)
>
> So I conclude Die temperature as retrieved over PECI is correct while
> DTS is mis-calculated. The old downstream code in OpenBMC was using
> ten_dot_six_to_millidegree() function for conversion, and that was
> providing expected results. And indeed if we reverse the calculation
> here we get 80000 - ((80000-67735) * 256 / 64) = 30940 which matches
> expectations.
--
With Best Regards,
Andy Shevchenko
