diff mbox

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

Message ID 1395243954-28262-2-git-send-email-dirk.j.brandewie@intel.com (mailing list archive)
State Accepted, archived
Headers show

Commit Message

dirk.brandewie@gmail.com March 19, 2014, 3:45 p.m. UTC
From: Dirk Brandewie <dirk.j.brandewie@intel.com>

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@intel.com>
---
 Documentation/cpu-freq/cpu-drivers.txt | 8 +++++++-
 drivers/cpufreq/cpufreq.c              | 3 ++-
 include/linux/cpufreq.h                | 1 +
 3 files changed, 10 insertions(+), 2 deletions(-)

Comments

Rafael J. Wysocki March 19, 2014, 10:31 p.m. UTC | #1
On Wednesday, March 19, 2014 08:45:53 AM dirk.brandewie@gmail.com wrote:
> From: Dirk Brandewie <dirk.j.brandewie@intel.com>
> 
> 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@intel.com>
> ---
>  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;
>
Rafael J. Wysocki March 20, 2014, 3:28 a.m. UTC | #2
On Wednesday, March 19, 2014 11:31:31 PM Rafael J. Wysocki wrote:
> On Wednesday, March 19, 2014 08:45:53 AM dirk.brandewie@gmail.com wrote:
> > From: Dirk Brandewie <dirk.j.brandewie@intel.com>
> > 
> > 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@intel.com>

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.

> > ---
> >  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;
> > 
> 
>
dirk.brandewie@gmail.com March 20, 2014, 3:01 p.m. UTC | #3
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@gmail.com wrote:
>>> From: Dirk Brandewie <dirk.j.brandewie@intel.com>
>>>
>>> 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@intel.com>
>
> 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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diff mbox

Patch

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);
 
 	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;