linux-kernel - Re: Cpufreq shutdown patch (kernel 2.6.35.3)

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Message-ID: <20120213162852.GA29947@redhat.com>
Date:	Mon, 13 Feb 2012 11:28:53 -0500
From:	Dave Jones <davej@...hat.com>
To:	"N. Coesel" <nico@...dev.nl>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Cpufreq shutdown patch (kernel 2.6.35.3)

On Thu, Jan 19, 2012 at 10:18:10PM +0100, N. Coesel wrote:
 
 > I've found a problem in drivers/cpufreq/cpufreq.c. The driver does 
 > not execute the exit member of the low level driver when shutting 
 > down for a reboot (reset). This potentially leaves the power supply 
 > at a too low voltage to boot the system properly. The patch below 
 > adds a shutdown function which executes the exit member of the low 
 > level driver which allows a system to be properly prepared for a reset.

I'm curious what hardware you saw this problem on ?

I've just seen a report on an x86 system which looks like it might
be solved by this.
https://bugzilla.redhat.com/show_bug.cgi?id=789964

 > --- drivers/cpufreq/cpufreq.c.orig      2010-08-20 20:55:55.000000000 +0200
 > +++ drivers/cpufreq/cpufreq.c   2012-01-19 21:50:46.000000000 +0100
 > @@ -1431,11 +1431,34 @@ fail:
 >          return ret;
 >   }
 > 
 > +
 > +static int cpufreq_shutdown(struct sys_device *sysdev)
 > +{
 > +       struct cpufreq_policy *cpu_policy;
 > +       int cpu = sysdev->id;
 > +       int ret =0;
 > +
 > +       if (!cpu_online(cpu))
 > +               return 0;
 > +
 > +       cpu_policy = cpufreq_cpu_get(cpu);
 > +       if (!cpu_policy)
 > +               return -EINVAL;
 > +
 > +//     printk("cpufreq_shutdown %d \n", cpu);
 > +       if (cpufreq_driver->exit)
 > +               ret = cpufreq_driver->exit(cpu_policy);
 > +
 > +       return ret;
 > +}
 > +
 > +
 >   static struct sysdev_driver cpufreq_sysdev_driver = {
 >          .add            = cpufreq_add_dev,
 >          .remove         = cpufreq_remove_dev,
 >          .suspend        = cpufreq_suspend,
 >          .resume         = cpufreq_resume,
 > +       .shutdown = cpufreq_shutdown,
 >   };

I'll queue this up, with the whitespace fixed, and commented out line removed.

	Dave

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