linux-kernel - Re: [PATCH] thermal: remove power allocator from list of default governors

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Message-ID: <20150805184938.GC4161@localhost.localdomain>
Date:	Wed, 5 Aug 2015 11:49:41 -0700
From:	Eduardo Valentin <edubezval@...il.com>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Javi Merino <javi.merino@....com>, Zhang Rui <rui.zhang@...el.com>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	Tushar Dave <tushar.n.dave@...el.com>,
	Lan Tianyu <tianyu.lan@...el.com>,
	Punit Agrawal <Punit.Agrawal@....com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] thermal: remove power allocator from list of default
 governors

On Wed, Aug 05, 2015 at 09:35:39AM -0700, Dmitry Torokhov wrote:
> On Wed, Aug 05, 2015 at 09:37:55AM +0100, Javi Merino wrote:
> > On Tue, Aug 04, 2015 at 05:39:21PM +0100, Dmitry Torokhov wrote:
> > > As it currently stands the power allocator governor can not handle
> > > thermal zones that are not specifically crafted and therefore can not be
> > > used as a default governor.
> > > 
> > > Users need to explicitly enable this governor for thermal zones that do
> > > have enough information for its operation.
> > > 
> > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> > > ---
> > >  drivers/thermal/Kconfig | 8 --------
> > >  1 file changed, 8 deletions(-)
> > > 
> > > diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> > > index 0390044..34d05d3 100644
> > > --- a/drivers/thermal/Kconfig
> > > +++ b/drivers/thermal/Kconfig
> > > @@ -82,14 +82,6 @@ config THERMAL_DEFAULT_GOV_USER_SPACE
> > >  	  Select this if you want to let the user space manage the
> > >  	  platform thermals.
> > >  
> > > -config THERMAL_DEFAULT_GOV_POWER_ALLOCATOR
> > > -	bool "power_allocator"
> > > -	select THERMAL_GOV_POWER_ALLOCATOR
> > > -	help
> > > -	  Select this if you want to control temperature based on
> > > -	  system and device power allocation. This governor can only
> > > -	  operate on cooling devices that implement the power API.
> > > -
> > 
> > Currently the only way we have for a thermal zone configured from
> > device tree to use a governor from the kernel boot is by using
> > THERMAL_DEFAULT_GOV_*.  If we remove this option some devices won't
> > have a workable thermal framework until userspace is up and running.
> 
> Why would step wise, or fair share be not workable (even if not optimal)
> thermal frameworks? It doe snot take that long to get to [early]
> userspace. Half of the boot time the thermal framework is not working
> anyway because half of the devices that can act as colling devices are
> not yet logically there.
> 
> > 
> > Would you rather have the power allocator governor accept every
> > thermal zone?
> 
> If it is to be one of default governors then yes, it needs to be able to
> manage all thermal zones, the same way as the other 3 governors can, as
> far as I know.

I believe fairshare also relies on platform data to be properly set,
otherwise, it would not be functional. That's probably why I overlooked
this point. That said, I would say, if we follow this logic, a similar
patch is needed for fairshare.

Javi, ideally, the governor would need to have a workable
default settings for any thermal zone that miss the platform settings.
Do you think it would be doable for power allocator?

BR,

> 
> Thanks.
> 
> -- 
> Dmitry

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