From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Bo Yan <byan@nvidia.com>
Cc: viresh.kumar@linaro.org, sgurrappadi@nvidia.com,
linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] cpufreq: skip cpufreq resume if it's not suspended
Date: Fri, 02 Feb 2018 12:54:17 +0100 [thread overview]
Message-ID: <17447147.z6jfkRxuEB@aspire.rjw.lan> (raw)
In-Reply-To: <913f1715-bdd0-1c03-ad76-38be9d3d2298@nvidia.com>
On Wednesday, January 24, 2018 9:53:14 PM CET Bo Yan wrote:
>
> On 01/23/2018 06:02 PM, Rafael J. Wysocki wrote:
> > On Tuesday, January 23, 2018 10:57:55 PM CET Bo Yan wrote:
> >> drivers/cpufreq/cpufreq.c | 4 ++++
> >> 1 file changed, 4 insertions(+)
> >>
> >> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> >> index 41d148af7748..95b1c4afe14e 100644
> >> --- a/drivers/cpufreq/cpufreq.c
> >> +++ b/drivers/cpufreq/cpufreq.c
> >> @@ -1680,6 +1680,10 @@ void cpufreq_resume(void)
> >> if (!cpufreq_driver)
> >> return;
> >>
> >> + if (unlikely(!cpufreq_suspended)) {
> >> + pr_warn("%s: resume after failing suspend\n", __func__);
> >> + return;
> >> + }
> >> cpufreq_suspended = false;
> >>
> >> if (!has_target() && !cpufreq_driver->resume)
> >>
> > Good catch, but rather than doing this it would be better to avoid
> > calling cpufreq_resume() at all if cpufreq_suspend() has not been called.
> Yes, I thought about that, but there is no good way to skip over it
> without introducing another flag. cpufreq_resume is called by
> dpm_resume, cpufreq_suspend is called by dpm_suspend. In the failure
> case, dpm_resume is called, but dpm_suspend is not. So on a higher level
> it's already unbalanced.
>
> One possibility is to rely on the pm_transition flag. So something like:
>
>
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index dc259d20c967..8469e6fc2b2c 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -842,6 +842,7 @@ static void async_resume(void *data, async_cookie_t
> cookie)
> void dpm_resume(pm_message_t state)
> {
> struct device *dev;
> + bool suspended = (pm_transition.event != PM_EVENT_ON);
> ktime_t starttime = ktime_get();
>
> trace_suspend_resume(TPS("dpm_resume"), state.event, true);
> @@ -885,7 +886,8 @@ void dpm_resume(pm_message_t state)
> async_synchronize_full();
> dpm_show_time(starttime, state, NULL);
>
> - cpufreq_resume();
> + if (likely(suspended))
> + cpufreq_resume();
> trace_suspend_resume(TPS("dpm_resume"), state.event, false);
> }
I was thinking about something else.
Anyway, I think your original patch is OK too, but without printing the
message. Just combine the cpufreq_suspended check with the cpufreq_driver
one and the unlikely() thing is not necessary.
Thanks,
Rafael
next prev parent reply other threads:[~2018-02-02 11:56 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-23 21:57 [PATCH] cpufreq: skip cpufreq resume if it's not suspended Bo Yan
2018-01-24 2:02 ` Rafael J. Wysocki
2018-01-24 20:53 ` Bo Yan
2018-02-02 11:54 ` Rafael J. Wysocki [this message]
2018-02-02 19:34 ` Saravana Kannan
2018-02-02 21:28 ` Bo Yan
2018-02-05 4:01 ` Viresh Kumar
2018-02-05 8:50 ` Rafael J. Wysocki
2018-02-05 9:05 ` Viresh Kumar
2018-02-15 21:27 ` Saravana Kannan
2018-02-15 22:06 ` Rafael J. Wysocki
2018-01-25 19:15 ` [PATCH v2] " Bo Yan
2018-02-05 9:19 ` [PATCH] " Rafael J. Wysocki
2018-02-05 9:23 ` Viresh Kumar
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