Date: Wed, 9 Sep 2009 11:20:51 -0700
From: "Darrick J. Wong" <djwong@us.ibm.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: akpm@linux-foundation.org, mm-commits@vger.kernel.org, lenb@kernel.org,
       rui.zhang@intel.com, linux-kernel <linux-kernel@vger.kernel.org>,
       lm-sensors <lm-sensors@lm-sensors.org>
Subject: Re: [PATCH v3] hwmon driver for ACPI 4.0 power meters
Message-ID: <20090909182051.GA26158@tux1.beaverton.ibm.com>
Reply-To: djwong@us.ibm.com
References: <200908202049.n7KKnKO7015060@imap1.linux-foundation.org> <20090820211557.GA8431@elf.ucw.cz> <20090820213755.GB10521@tux1.beaverton.ibm.com> <20090821091939.GC21167@elf.ucw.cz> <20090821184718.GD23397@tux1.beaverton.ibm.com> <20090821221705.GA2108@elf.ucw.cz> <20090822011744.GH10521@tux1.beaverton.ibm.com> <20090821140159.GB1328@ucw.cz> <20090908202410.GS10521@tux1.beaverton.ibm.com> <20090909080637.GA28353@elf.ucw.cz>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20090909080637.GA28353@elf.ucw.cz>
User-Agent: Mutt/1.5.17+20080114 (2008-01-14)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 2098
Lines: 67

On Wed, Sep 09, 2009 at 10:06:38AM +0200, Pavel Machek wrote:

> > +Description
> > +-----------
> > +
> > +This driver implements sensor reading support for the power meters exposed in
> > +the ACPI 4.0 spec (Chapter 10.4).  These devices have a simple set of
> > +features--a power meter that returns average power use over a configurable
> > +interval, an optional capping mechanism, and a couple of trip points.
> 
> So where do we get the average power?

/sys/class/hwmon/hwmonX/device/powerX_average.  Most of the hwmon driver
documentation assumes the reader has read the contents of
Documentation/hwmon/sysfs-interface, but I suppose it wouldn't be too
difficult to call that out explicitly.

(Actually I think you're really supposed to use libsensors and not access sysfs
directly.)

> > +Special Features
> > +----------------
> > +
> > +The power[1-*]_is_battery knob indicates if the power supply is a battery.
> > +Both power[1-*]_average_{min,max} must be set before the trip
> > points will work.
> 
> How do trip points work? It is not explained here.

Will add that too.

> > +config ACPI_POWER_METER
> > +	tristate "ACPI 4.0 power meter"
> > +	depends on HWMON
> > +	default m
> 
> default M is "evil".

I'll change it to Y, but I wonder why you think default M is evil...?

> > +	  devices.  Say Y (or M) if you have an Intel or AMD computer with
> > +	  a power meter.
> 
> WTF? Neither Intel nor AMD makes _computers_.

I'll change that to "a computer with ACPI firmware."

> > +	  To compile this driver as a module, choose M here:
> > +	  the module will be called power-meter.
> 
> .ko.

The other config options in drivers/acpi/Kconfig omit the .ko; I was trying to
be consistent with them.

> > +#define POWER_CAP_NAME		"power1_cap"
> 
> I did not see power cap explained.

I'll add that, thanks for the continued review!

--D
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/