From: Viresh Kumar <viresh.kumar@linaro•org>
To: "Rafael J. Wysocki" <rafael@kernel•org>
Cc: Guenter Roeck <linux@roeck-us•net>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel•com>,
linux-next@vger•kernel.org,
Linux Kernel Mailing List <linux-kernel@vger•kernel.org>,
"linux-arm-kernel@lists•infradead.org"
<linux-arm-kernel@lists•infradead.org>,
"linux-pm@vger•kernel.org" <linux-pm@vger•kernel.org>,
Peter Zijlstra <peterz@infradead•org>
Subject: Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace timers with utilization ...'
Date: Tue, 16 Feb 2016 06:43:35 +0530 [thread overview]
Message-ID: <20160216011335.GI6334@vireshk-i7> (raw)
In-Reply-To: <CAJZ5v0gLankSuziQq25qTCyNqeOX43yD9jnJu_XXwbdyajfmKg@mail.gmail.com>
On 15-02-16, 19:41, Rafael J. Wysocki wrote:
> On Mon, Feb 15, 2016 at 6:05 PM, Guenter Roeck <linux@roeck-us•net> wrote:
> > [ 1.340000] [<c0958e78>] (__cpufreq_driver_target) from [<c095ca58>] (dbs_check_cpu+0x1ac/0x1e8)
> > [ 1.340000] [<c095ca58>] (dbs_check_cpu) from [<c095cd04>] (cpufreq_governor_dbs+0x1fc/0x608)
> > [ 1.340000] [<c095cd04>] (cpufreq_governor_dbs) from [<c0959c5c>] (__cpufreq_governor+0x1a8/0x204)
> > [ 1.340000] [<c0959c5c>] (__cpufreq_governor) from [<c095a2dc>] (cpufreq_init_policy+0x60/0x8c)
> > [ 1.340000] [<c095a2dc>] (cpufreq_init_policy) from [<c095a5f0>] (cpufreq_online+0x2e8/0x708)
> > [ 1.340000] [<c095a5f0>] (cpufreq_online) from [<c075674c>] (subsys_interface_register+0x80/0xc4)
> > [ 1.340000] [<c075674c>] (subsys_interface_register) from [<c0959764>] (cpufreq_register_driver+0x144/0x1a0)
>
> This is the registration of the cpufreq driver (cpufreq-dt in this case).
>
> It does cpufreq_online()->cpufreq_init_policy()->__cpufreq_governor()->cpufreq_governor_dbs()->dbs_check_cpu().
>
> The only way that can happen is when cpufreq_set_policy() finds that
> the "old" and the "new" policies use the same governor, so it goes and
> calls __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS), but I'm not sure
> how this is possible during the initialization ATM.
>
> Viresh, any ideas?
You misread probably.
During init, policy->gov is NULL and new_policy->gov is set to the
default one, probably ondemand/conservative. And in that case, we do:
- INIT
- START
- LIMITS
So above sequence is guaranteed to happen rather.
--
viresh
next prev parent reply other threads:[~2016-02-16 1:13 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-15 17:05 Crashes in arm qemu emulations due to 'cpufreq: governor: Replace timers with utilization ...' Guenter Roeck
2016-02-15 18:41 ` Rafael J. Wysocki
2016-02-15 18:49 ` Rafael J. Wysocki
2016-02-15 18:49 ` Marc Zyngier
2016-02-15 18:54 ` Rafael J. Wysocki
2016-02-15 19:03 ` Marc Zyngier
2016-02-15 19:12 ` Rafael J. Wysocki
2016-02-15 19:28 ` Rafael J. Wysocki
2016-02-15 19:42 ` Tony Lindgren
2016-02-15 19:46 ` Guenter Roeck
2016-02-15 19:57 ` Tony Lindgren
2016-02-15 19:23 ` Russell King - ARM Linux
2016-02-15 20:41 ` Rafael J. Wysocki
2016-02-15 19:07 ` Russell King - ARM Linux
2016-02-15 19:01 ` Tony Lindgren
2016-02-15 19:40 ` Guenter Roeck
2016-02-15 19:58 ` Tony Lindgren
2016-02-15 20:09 ` Guenter Roeck
2016-02-15 20:38 ` Rafael J. Wysocki
2016-02-15 20:37 ` Rafael J. Wysocki
2016-02-15 21:36 ` Tony Lindgren
2016-02-16 1:38 ` Guenter Roeck
2016-02-15 19:02 ` Russell King - ARM Linux
2016-02-16 1:13 ` Viresh Kumar [this message]
2016-02-16 1:27 ` Rafael J. Wysocki
2016-02-16 1:36 ` Viresh Kumar
2016-02-15 22:29 ` Peter Maydell
2016-02-15 23:19 ` Guenter Roeck
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