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SubjectRe: Cpufreq shutdown patch (kernel 2.6.35.3)
On Mon, Feb 13, 2012 at 11:28:53AM -0500, Dave Jones wrote:
> 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.

Except I can't of course, because we no longer have a sysdev driver
since 8a25a2fd126c621f44f3aeaef80d51f00fc11639
Kay, given the subsys_interface doesn't have a shutdown method, what should
this be doing ?

Dave


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