On Mon, 2021-11-29 at 19:20 -0800, Ricardo Neri wrote:
> On Wed, Nov 24, 2021 at 03:09:20PM +0100, Rafael J. Wysocki wrote:
> > On Sat, Nov 6, 2021 at 2:34 AM Ricardo Neri
> > <ricardo.neri-calderon@xxxxxxxxxxxxxxx> wrote:
> > >
> > > The Intel Hardware Feedback Interface provides guidance to the
> > > operating
> > > system about the performance and energy efficiency capabilities
> > > of each
> > > CPU in the system. Capabilities are numbers between 0 and 255
> > > where a
> > > higher number represents a higher capability. For each CPU,
> > > energy
> > > efficiency and performance are reported as separate capabilities.
> > >
> > > Hardware computes these capabilities based on the operating
> > > conditions of
> > > the system such as power and thermal limits. These capabilities
> > > are shared
> > > with the operating system in a table resident in memory. Each
> > > package in
> > > the system has its own HFI instance. Every logical CPU in the
> > > package is
> > > represented in the table. More than one logical CPUs may be
> > > represented in
> > > a single table entry. When the hardware updates the table, it
> > > generates a
> > > package-level thermal interrupt.
> > >
> > > The size and format of the HFI table depend on the supported
> > > features and
> > > can only be determined at runtime. To minimally initialize the
> > > HFI, parse
> > > its features and allocate one instance per package of a data
> > > structure with
> > > the necessary parameters to read and navigate individual HFI
> > > tables.
> > >
> > > A subsequent changeset will provide per-CPU initialization and
> > > interrupt
> > > handling.
> > >
[...]
> > > + /*
> > > + * If we are here we know that CPUID_HFI_LEAF exists.
> > > Parse the
> > > + * supported capabilities and the size of the HFI table.
> > > + */
> > > + reg = cpuid_edx(CPUID_HFI_LEAF);
> > > +
> > > + hfi_features.capabilities = reg & HFI_CAPABILITIES_MASK;
> > > + if (!(hfi_features.capabilities &
> > > HFI_CAPABILITIES_PERFORMANCE)) {
> > > + pr_err("Performance reporting not supported! Not
> > > using HFI\n");
> >
> > This doesn't need to be pr_err().
>
> Should it be a pr_warn() or perhaps pr_info()?
May be even pr_debug as we can always enable dynamic debug, where we
need to debug.
Thanks,
Srinivas
>
> Thanks and BR,
> Ricardo
>
