On Thu, Dec 29, 2022 at 1:58 PM Pratyush Yadav <ptyadav@xxxxxxxxx> wrote:
>
> Hi Rafael,
>
> On Wed, Dec 28 2022, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> >
> > When _PPC returns 0, it means that the CPU frequency is not limited by
> > the platform firmware, so make acpi_processor_get_platform_limit()
> > update the frequency QoS request used by it to "no limit" in that case.
> >
> > This addresses a problem with limiting CPU frequency artificially on
> > some systems after CPU offline/online to the frequency that corresponds
> > to the first entry in the _PSS return package.
> >
> > Reported-by: Pratyush Yadav <ptyadav@xxxxxxxxx>
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > ---
> >
> > v1 -> v2:
> > * Move some changes into a separate patch
> > * Update the changelog accordingly
> >
> > ---
> > drivers/acpi/processor_perflib.c | 20 ++++++++++++++++----
> > 1 file changed, 16 insertions(+), 4 deletions(-)
> >
> > Index: linux-pm/drivers/acpi/processor_perflib.c
> > ===================================================================
> > --- linux-pm.orig/drivers/acpi/processor_perflib.c
> > +++ linux-pm/drivers/acpi/processor_perflib.c
> > @@ -53,6 +53,8 @@ static int acpi_processor_get_platform_l
> > {
> > acpi_status status = 0;
> > unsigned long long ppc = 0;
> > + s32 qos_value;
> > + int index;
> > int ret;
> >
> > if (!pr)
> > @@ -72,17 +74,27 @@ static int acpi_processor_get_platform_l
> > }
> > }
> >
> > + index = ppc;
> > +
> > pr_debug("CPU %d: _PPC is %d - frequency %s limited\n", pr->id,
> > - (int)ppc, ppc ? "" : "not");
> > + index, index ? "is" : "is not");
> >
> > - pr->performance_platform_limit = (int)ppc;
> > + pr->performance_platform_limit = index;
> >
> > if (ppc >= pr->performance->state_count ||
> > unlikely(!freq_qos_request_active(&pr->perflib_req)))
> > return 0;
> >
> > - ret = freq_qos_update_request(&pr->perflib_req,
> > - pr->performance->states[ppc].core_frequency * 1000);
> > + /*
> > + * If _PPC returns 0, it means that all of the available states can be
> > + * used ("no limit").
> > + */
> > + if (index == 0)
> > + qos_value = FREQ_QOS_MAX_DEFAULT_VALUE;
>
> One small thing I noticed: in acpi_processor_ppc_init() "no limit" value
> is set to INT_MAX and here it is set to FREQ_QOS_MAX_DEFAULT_VALUE. Both
> should evaluate to the same value but I think it would be nice if the
> same thing is used in both places. Perhaps you can fix that up when
> applying?
Yes, I'll do that.
> Other than this,
>
> Reviewed-by: Pratyush Yadav <ptyadav@xxxxxxxxx>
> Tested-by: Pratyush Yadav <ptyadav@xxxxxxxxx>
Thanks!
> Thanks for working on this.
You're welcome.
