Re: [PATCH v5 0/3] cpufreq: cppc: Handle Highest Performance changes at runtime

[Rafael J. Wysocki (Intel)]

On Mon, Sep 21, 2026 at 9:47 PM Christian Loehle
<christian.loehle@xxxxxxx> wrote:
>
> On 9/7/26 09:49, Jie Zhan wrote:
> >
> >
> > On 8/7/2026 2:08 PM, Xueqin Luo wrote:
> >> Hi Rafael, Pierre,
> >>
> >> This series adds support for handling ACPI CPPC Highest Performance
> >> register changes at runtime, triggered by Notify(0x85) on a processor
> >> device.
> >>
> >> When the platform changes the Highest Performance value (e.g. due to
> >> thermal or power budget adjustments), the OSPM must re-evaluate the
> >> cached capability and propagate the change to the cpufreq policy,
> >> the scheduler's CPU capacity model, and the frequency invariance
> >> engine.
> > Any real use case of this on platforms that run cppc_cpufreq drivers?
> > Some addtional motivation may help.
> >
> > For example, a processor can age over time and its core frequency degrades.
> > It's good if platforms can make OSPM and userspace aware of this.
>
> +1

FWIW, this may be related to platform operating mode changes between
"performance" and "powersave" (longer battery life) if the top-most
OPP is a high-cost one.