On Mon, Mar 31, 2025 at 9:38 AM Zhang, Rui <rui.zhang@xxxxxxxxx> wrote:
>
> > -----Original Message-----
> > From: Giovanni Gherdovich <ggherdovich@xxxxxxx>
> > Sent: Friday, March 28, 2025 10:31 PM
> > To: Rafael J . Wysocki <rafael@xxxxxxxxxx>; Zhang, Rui <rui.zhang@xxxxxxxxx>
> > Cc: Len Brown <lenb@xxxxxxxxxx>; Giovanni Gherdovich
> > <ggherdovich@xxxxxxx>; linux-acpi@xxxxxxxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx; linux-pm@xxxxxxxxxxxxxxx
> > Subject: [PATCH 2/2] ACPI: processor: idle: Remove obsolete comment
> > Importance: High
> >
> > Since commit 496121c02127e9c460b436244c38260b044cc45a ("ACPI:
> > processor:
> > idle: Allow probing on platforms with one ACPI C-state"), the comment
> > doesn't reflect the code anymore; remove it.
> >
> > Signed-off-by: Giovanni Gherdovich <ggherdovich@xxxxxxx>
> > ---
> > drivers/acpi/processor_idle.c | 4 ----
> > 1 file changed, 4 deletions(-)
> >
> > diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> > index b181f7fc2090..2a076c7a825a 100644
> > --- a/drivers/acpi/processor_idle.c
> > +++ b/drivers/acpi/processor_idle.c
> > @@ -482,10 +482,6 @@ static int acpi_processor_get_cstate_info(struct
> > acpi_processor *pr)
> >
> > pr->power.count = acpi_processor_power_verify(pr);
> >
> > - /*
> > - * if one state of type C2 or C3 is available, mark this
> > - * CPU as being "idle manageable"
> > - */
> > for (i = 1; i < ACPI_PROCESSOR_MAX_POWER; i++) {
> > if (pr->power.states[i].valid) {
> > pr->power.count = i;
> > --
> > 2.43.0
>
> I think we can clean up a bit more. How about the patch below?
>
> From 115d3a07febff32eed49f9343ef111e7e1452f9d Mon Sep 17 00:00:00 2001
> From: "Zhang, Rui" <rui.zhang@xxxxxxxxx>
> Date: Mon, 31 Mar 2025 07:29:57 +0000
> Subject: [PATCH] ACPI: processor: idle: Simplify
> acpi_processor_get_cstate_info() logic
>
> Since commit 496121c02127 ("ACPI: processor: idle: Allow probing on
> platforms with one ACPI C-state"), acpi_idle driver can be probed with
> C1 only.
>
> Optimize the logic for setting pr->power.count and pr->flags.power by
> 1. unconditionally set pr->flags.power leveraging the fact that C1 is
> always valid after acpi_processor_get_power_info_default().
> 2. update acpi_processor_power_verify() to return the highest valid
> C-state directly.
>
> No functional change intended.
>
> Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
> ---
> drivers/acpi/processor_idle.c | 15 ++-------------
> 1 file changed, 2 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index 698897b29de2..7ce8c3802937 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -442,7 +442,7 @@ static int acpi_processor_power_verify(struct acpi_processor *pr)
>
> lapic_timer_check_state(i, pr, cx);
> tsc_check_state(cx->type);
> - working++;
> + working = i;
What if some states are skipped because they are invalid? 'working'
can be less than 'i' then AFAICS.
> }
>
> if (buggy_latency) {
> @@ -457,7 +457,6 @@ static int acpi_processor_power_verify(struct acpi_processor *pr)
>
> static int acpi_processor_get_cstate_info(struct acpi_processor *pr)
> {
> - unsigned int i;
> int result;
>
>
> @@ -477,17 +476,7 @@ static int acpi_processor_get_cstate_info(struct acpi_processor *pr)
> acpi_processor_get_power_info_default(pr);
>
> pr->power.count = acpi_processor_power_verify(pr);
> -
> - /*
> - * if one state of type C2 or C3 is available, mark this
> - * CPU as being "idle manageable"
> - */
> - for (i = 1; i < ACPI_PROCESSOR_MAX_POWER; i++) {
> - if (pr->power.states[i].valid) {
> - pr->power.count = i;
> - pr->flags.power = 1;
> - }
> - }
> + pr->flags.power = 1;
>
> return 0;
> }
> --
