Re: [PATCH 1/2] cpufreq: Add stop callback to cpufreq_driver interface

[Dirk Brandewie]

On 03/19/2014 08:28 PM, Rafael J. Wysocki wrote:
> On Wednesday, March 19, 2014 11:31:31 PM Rafael J. Wysocki wrote:
> > On Wednesday, March 19, 2014 08:45:53 AM dirk.brandewie@xxxxxxxxx wrote:
> > > From: Dirk Brandewie <dirk.j.brandewie@xxxxxxxxx>
> > >
> > > This callback allows the driver to do clean up before the CPU is
> > > completely down and its state cannot be modified.  This is used
> > > by the intel_pstate driver to reduce the requested P state prior to
> > > the core going away.  This is required because the requested P state
> > > of the offline core is used to select the package P state. This
> > > effectively sets the floor package P state to the requested P state on
> > > the offline core.
> > >
> > > Signed-off-by: Dirk Brandewie <dirk.j.brandewie@xxxxxxxxx>
>
> To speed up things a bit I changed the name of the new callback to ->stop_cpu
> and made it void.
>
> I also modified patch [2/2] accordingly and queued the both of them up for 3.15.
>
> Please check the bleeding-edge branch.
>
> I wouldn't like to need to do anything like that any more in the future, though.

Sorry had appointments yesterday afternoon.

bleeding-edge looks good


> > > ---
> > >   Documentation/cpu-freq/cpu-drivers.txt | 8 +++++++-
> > >   drivers/cpufreq/cpufreq.c              | 3 ++-
> > >   include/linux/cpufreq.h                | 1 +
> > >   3 files changed, 10 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt
> > > index 8b1a445..79def80 100644
> > > --- a/Documentation/cpu-freq/cpu-drivers.txt
> > > +++ b/Documentation/cpu-freq/cpu-drivers.txt
> > > @@ -61,7 +61,13 @@ target_index		-	See below on the differences.
> > >
> > >   And optionally
> > >
> > > -cpufreq_driver.exit -		A pointer to a per-CPU cleanup function.
> > > +cpufreq_driver.exit -		A pointer to a per-CPU cleanup
> > > +		    		function called during CPU_POST_DEAD
> > > +		    		phase of cpu hotplug process.
> > > +
> > > +cpufreq_driver.stop -		A pointer to a per-CPU stop function
> > > +			    	called during CPU_DOWN_PREPARE phase of
> > > +				cpu hotplug process.
> > >
> > >   cpufreq_driver.resume -		A pointer to a per-CPU resume function
> > >   				which is called with interrupts disabled
> > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> > > index cf485d9..bb20292 100644
> > > --- a/drivers/cpufreq/cpufreq.c
> > > +++ b/drivers/cpufreq/cpufreq.c
> > > @@ -1336,7 +1336,8 @@ static int __cpufreq_remove_dev_prepare(struct device *dev,
> > >   						__func__, new_cpu, cpu);
> > >   			}
> > >   		}
> > > -	}
> > > +	} else if (cpufreq_driver->stop && cpufreq_driver->setpolicy)
> > > +		cpufreq_driver->stop(policy);
> >
> > Nit: Why is it an int function if the only caller doesn't check the
> > return value?  It should be void.
> >
> > >   	return 0;
> > >   }
> > > diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> > > index 4d89e0e..ff8db19 100644
> > > --- a/include/linux/cpufreq.h
> > > +++ b/include/linux/cpufreq.h
> > > @@ -224,6 +224,7 @@ struct cpufreq_driver {
> > >   	int	(*bios_limit)	(int cpu, unsigned int *limit);
> > >
> > >   	int	(*exit)		(struct cpufreq_policy *policy);
> > > +	int	(*stop)		(struct cpufreq_policy *policy);
> > >   	int	(*suspend)	(struct cpufreq_policy *policy);
> > >   	int	(*resume)	(struct cpufreq_policy *policy);
> > >   	struct freq_attr	**attr;

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