Re: [PATCH v2] thermal: re-calculate k_po/k_pu when update sustainable power

[Javi Merino <javi.merino@arm.com>]

On Fri, Jan 01, 2016 at 08:03:47AM +0800, Leo Yan wrote:
> Hi Eduardo,
> 
> Thanks for review.
> 
> On Thu, Dec 31, 2015 at 09:21:26AM -0800, Eduardo Valentin wrote:
> > On Wed, Dec 30, 2015 at 06:38:40PM +0800, Leo Yan wrote:
> > > k_po/k_pu are in essence ratio values compared with sustainable power.
> > > So when update sustainable power, we can recalculate k_po/k_pu simply
> > > with below formula:
> > > 
> > >                sustainable_power(new)
> > >     k_p(new) = ---------------------- * k_p(old)
> > >                sustainable_power(old)
> > > 
> > > Signed-off-by: Leo Yan <leo.yan@linaro.org>
> > > ---
> > >  drivers/thermal/thermal_core.c | 6 +++++-
> > >  1 file changed, 5 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> > > index d9e525c..223f8df 100644
> > > --- a/drivers/thermal/thermal_core.c
> > > +++ b/drivers/thermal/thermal_core.c
> > > @@ -908,7 +908,7 @@ sustainable_power_store(struct device *dev, struct device_attribute *devattr,
> > >  			const char *buf, size_t count)
> > >  {
> > >  	struct thermal_zone_device *tz = to_thermal_zone(dev);
> > > -	u32 sustainable_power;
> > > +	u32 sustainable_power, old_val;
> > >  
> > >  	if (!tz->tzp)
> > >  		return -EIO;
> > > @@ -916,8 +916,12 @@ sustainable_power_store(struct device *dev, struct device_attribute *devattr,
> > >  	if (kstrtou32(buf, 10, &sustainable_power))
> > >  		return -EINVAL;
> > >  
> > > +	old_val = tz->tzp->sustainable_power;
> > > +
> > >  	tz->tzp->sustainable_power = sustainable_power;
> > >  
> > > +	tz->tzp->k_po = (tz->tzp->k_po * sustainable_power) / old_val;
> > > +	tz->tzp->k_pu = (tz->tzp->k_pu * sustainable_power) / old_val;
> > 
> > I believe this has to be done by the governor. These properties are
> > power_allocator specific. thermal_core should not really care about
> > them.
> 
> Okay, I will try to update these properties in power_allocator.c.
> Javi, do you think this is fine for you?

Yes, I'm happy with the idea.  If Eduardo prefers this in
power_allocator.c, let's do it there :)

Javi