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Date: Thu, 5 Dec 2019 13:02:27 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>,
Linux PM <linux-pm@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>,
Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
Len Brown <len.brown@...el.com>, Len Brown <lenb@...nel.org>,
Rafael Wysocki <rafael@...nel.org>,
Yoshinori Sato <ysato@...rs.sourceforge.jp>,
Rich Felker <dalias@...c.org>,
Linux-sh list <linux-sh@...r.kernel.org>
Subject: Re: [PATCH 1/2] cpuidle: Drop disabled field from struct cpuidle_state
On Thu, Dec 5, 2019 at 12:15 PM Daniel Lezcano
<daniel.lezcano@...aro.org> wrote:
>
> On 21/11/2019 19:41, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >
> > After recent cpuidle updates the "disabled" field in struct
> > cpuidle_state is only used by two drivers (intel_idle and shmobile
> > cpuidle) for marking unusable idle states, but that may as well be
> > achieved with the help of a state flag, so define an "unusable" idle
> > state flag, CPUIDLE_FLAG_UNUSABLE, make the drivers in question use
> > it instead of the "disabled" field and make the core set
> > CPUIDLE_STATE_DISABLED_BY_DRIVER for the idle states with that flag
> > set.
> >
> > After the above changes, the "disabled" field in struct cpuidle_state
> > is not used any more, so drop it.
> >
> > No intentional functional impact.
> >
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > ---
> >
> > Changes from RFC:
> >
> > - Do not add extra braces (unrelated to the rest of the patch).
> >
> > ---
> > arch/sh/kernel/cpu/shmobile/cpuidle.c | 8 ++++----
> > drivers/cpuidle/cpuidle.c | 2 +-
> > drivers/cpuidle/poll_state.c | 1 -
> > drivers/idle/intel_idle.c | 6 +++---
> > include/linux/cpuidle.h | 2 +-
> > 5 files changed, 9 insertions(+), 10 deletions(-)
> >
> > Index: linux-pm/drivers/idle/intel_idle.c
> > ===================================================================
> > --- linux-pm.orig/drivers/idle/intel_idle.c
> > +++ linux-pm/drivers/idle/intel_idle.c
> > @@ -1291,8 +1291,8 @@ static void sklh_idle_state_table_update
> > return;
> > }
> >
> > - skl_cstates[5].disabled = 1; /* C8-SKL */
> > - skl_cstates[6].disabled = 1; /* C9-SKL */
> > + skl_cstates[5].flags |= CPUIDLE_FLAG_UNUSABLE; /* C8-SKL */
> > + skl_cstates[6].flags |= CPUIDLE_FLAG_UNUSABLE; /* C9-SKL */
> > }
> > /*
> > * intel_idle_state_table_update()
> > @@ -1355,7 +1355,7 @@ static void __init intel_idle_cpuidle_dr
> > continue;
> >
> > /* if state marked as disabled, skip it */
> > - if (cpuidle_state_table[cstate].disabled != 0) {
> > + if (cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_UNUSABLE) {
> > pr_debug("state %s is disabled\n",
> > cpuidle_state_table[cstate].name);
> > continue;
> > Index: linux-pm/include/linux/cpuidle.h
> > ===================================================================
> > --- linux-pm.orig/include/linux/cpuidle.h
> > +++ linux-pm/include/linux/cpuidle.h
> > @@ -54,7 +54,6 @@ struct cpuidle_state {
> > unsigned int exit_latency; /* in US */
> > int power_usage; /* in mW */
> > unsigned int target_residency; /* in US */
> > - bool disabled; /* disabled on all CPUs */
> >
> > int (*enter) (struct cpuidle_device *dev,
> > struct cpuidle_driver *drv,
> > @@ -77,6 +76,7 @@ struct cpuidle_state {
> > #define CPUIDLE_FLAG_POLLING BIT(0) /* polling state */
> > #define CPUIDLE_FLAG_COUPLED BIT(1) /* state applies to multiple cpus */
> > #define CPUIDLE_FLAG_TIMER_STOP BIT(2) /* timer is stopped on this state */
> > +#define CPUIDLE_FLAG_UNUSABLE BIT(3) /* avoid using this state */
> >
> > struct cpuidle_device_kobj;
> > struct cpuidle_state_kobj;
> > Index: linux-pm/arch/sh/kernel/cpu/shmobile/cpuidle.c
> > ===================================================================
> > --- linux-pm.orig/arch/sh/kernel/cpu/shmobile/cpuidle.c
> > +++ linux-pm/arch/sh/kernel/cpu/shmobile/cpuidle.c
> > @@ -67,7 +67,7 @@ static struct cpuidle_driver cpuidle_dri
> > .enter = cpuidle_sleep_enter,
> > .name = "C2",
> > .desc = "SuperH Sleep Mode [SF]",
> > - .disabled = true,
> > + .flags = CPUIDLE_FLAG_UNUSABLE,
> > },
> > {
> > .exit_latency = 2300,
> > @@ -76,7 +76,7 @@ static struct cpuidle_driver cpuidle_dri
> > .enter = cpuidle_sleep_enter,
> > .name = "C3",
> > .desc = "SuperH Mobile Standby Mode [SF]",
> > - .disabled = true,
> > + .flags = CPUIDLE_FLAG_UNUSABLE,
> > },
> > },
> > .safe_state_index = 0,
> > @@ -86,10 +86,10 @@ static struct cpuidle_driver cpuidle_dri
> > int __init sh_mobile_setup_cpuidle(void)
> > {
> > if (sh_mobile_sleep_supported & SUSP_SH_SF)
> > - cpuidle_driver.states[1].disabled = false;
> > + cpuidle_driver.states[1].flags = CPUIDLE_FLAG_NONE;
>
> That will overwrite other flags value, bit operation should be used here
> to remove CPUIDLE_FLAG_UNUSABLE.
This is based on the observation that the other flags are not set by
this driver anyway.
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