linux-kernel - RE: [PATCH 4/8] Thermal: Add Thermal

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Date:	Thu, 20 Dec 2012 18:12:55 +0000
From:	"R, Durgadoss" <durgadoss.r@...el.com>
To:	Greg KH <gregkh@...uxfoundation.org>
CC:	"Zhang, Rui" <rui.zhang@...el.com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"hongbo.zhang@...aro.org" <hongbo.zhang@...aro.org>,
	"wni@...dia.com" <wni@...dia.com>
Subject: RE: [PATCH 4/8] Thermal: Add Thermal_trip sysfs node

> -----Original Message-----
> From: Greg KH [mailto:gregkh@...uxfoundation.org]
> Sent: Thursday, December 20, 2012 11:21 PM
> To: R, Durgadoss
> Cc: Zhang, Rui; linux-pm@...r.kernel.org; linux-kernel@...r.kernel.org;
> hongbo.zhang@...aro.org; wni@...dia.com
> Subject: Re: [PATCH 4/8] Thermal: Add Thermal_trip sysfs node
> 
> On Thu, Dec 20, 2012 at 04:58:32PM +0000, R, Durgadoss wrote:
> > > -----Original Message-----
> > > From: Greg KH [mailto:gregkh@...uxfoundation.org]
> > > Sent: Thursday, December 20, 2012 10:09 PM
> > > To: R, Durgadoss
> > > Cc: Zhang, Rui; linux-pm@...r.kernel.org; linux-kernel@...r.kernel.org;
> > > hongbo.zhang@...aro.org; wni@...dia.com
> > > Subject: Re: [PATCH 4/8] Thermal: Add Thermal_trip sysfs node
> > >
> > > On Thu, Dec 20, 2012 at 04:25:32PM +0000, R, Durgadoss wrote:
> > > >
> > > > > -----Original Message-----
> > > > > From: Greg KH [mailto:gregkh@...uxfoundation.org]
> > > > > Sent: Thursday, December 20, 2012 9:42 PM
> > > > > To: R, Durgadoss
> > > > > Cc: Zhang, Rui; linux-pm@...r.kernel.org; linux-
> kernel@...r.kernel.org;
> > > > > hongbo.zhang@...aro.org; wni@...dia.com
> > > > > Subject: Re: [PATCH 4/8] Thermal: Add Thermal_trip sysfs node
> > > > >
> > > > > On Thu, Dec 20, 2012 at 07:52:03AM +0000, R, Durgadoss wrote:
> > > > > > > On Tue, Dec 18, 2012 at 02:59:33PM +0530, Durgadoss R wrote:
> > > > > > > > This patch adds a thermal_trip directory under
> > > > > > > > /sys/class/thermal/zoneX. This directory contains
> > > > > > > > the trip point values for sensors bound to this
> > > > > > > > zone.
> > > > > > >
> > > > > > > Eeek, you just broke userspace tools that now can no longer see
> > > these
> > > > > > > entries :(
> > > > > > >
> > > > > > > Why do you need to create a subdirectory?  As you found out,
> doing
> > > so
> > > > > > > isn't the easiest, right?  That is on purpose.
> > > > > >
> > > > > > Yes, I observed the complexity.
> > > > > >
> > > > > > >
> > > > > > > I really wouldn't recommend doing this at all, please stick within
> the
> > > > > > > 'struct device' framework here, don't create new kobjects and
> hang
> > > sysfs
> > > > > > > files off of them.
> > > > > >
> > > > > > But, we cannot put all _trip directly under ZoneX directory.
> > > > >
> > > > > Why not?  What is preventing this?
> > > > >
> > > > > > We can remove the thermal_trip directory, and put sensorY_trip
> under
> > > > > > /sys/class/thermal/zoneX/.  But this sensorY_trip needs to be a
> > > > > > directory which has four sysfs nodes named, active, passive, crit,
> > > > > > hot.
> > > > > >
> > > > > > Rui, What do you think about this ?
> > > > > >
> > > > > > The only other way I see, is directly put
> > > > > sensorY_trip_[active/passive/hot/crit]
> > > > > > which will create way too many nodes, under
> > > /sys/class/thermal/zoneX/.
> > > > >
> > > > > What is "too many"?  20000?  50000?  How many are we talking about
> > > here?
> > > >
> > > > Not in 1000's though..
> > > >
> > > > > What is the limiting factor that is preventing this from all going into
> > > > > one directory?
> > > >
> > > > We support a MAX of 12 sensors per zone today, which will lead to
> > > > 12 * 4, 48 nodes under this directory named
> > > > sensorY_trip_[active/passive/hot/crit], besides the other nodes.
> > >
> > > That's fine, we can easily support that many files, have you tried this
> > > already?
> >
> > Yes, in fact, this is sort of what was the old implementation..
> > although with different sysfs nodes.
> 
> What "old" implementation, one that is in-kernel?  Are you changing the
> user interface here?

Sorry, I should have used better wordings ;(
[s/old/existing]
There are other sysfs nodes following the correct convention under
/sys/class/thermal/, which is what I was mentioning.

No, we are not changing the user interface, in these patches.

Thanks,
Durga
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