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From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        "Kristen C. Accardi" <kristen.c.accardi@intel.com>,
        Len Brown <lenb@kernel.org>
Subject: Re: [RFC][Update 2][PATCH 1/4] ACPI / PM: Export power states of ACPI devices via sysfs
Date: Mon, 21 Jan 2013 23:27:32 +0100
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On Monday, January 21, 2013 12:53:05 PM Greg Kroah-Hartman wrote:
> On Mon, Jan 21, 2013 at 02:04:32PM +0100, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > 
> > Make it possible to retrieve the current power state of a device with
> > ACPI power management from user space via sysfs by adding a new
> > attribute power_state to the sysfs directory associated with the
> > struct acpi_device object representing the device's ACPI node.
> > 
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > ---
> >  Documentation/ABI/testing/sysfs-devices-power_state |   21 ++++++++++++++
> >  drivers/acpi/scan.c                                 |   29 +++++++++++++++++++-
> >  2 files changed, 49 insertions(+), 1 deletion(-)
> > 
> > Index: linux-pm/drivers/acpi/scan.c
> > ===================================================================
> > --- linux-pm.orig/drivers/acpi/scan.c
> > +++ linux-pm/drivers/acpi/scan.c
> > @@ -178,6 +178,23 @@ err_out:
> >  }
> >  EXPORT_SYMBOL(acpi_bus_hot_remove_device);
> >  
> > +static ssize_t power_state_show(struct device *dev,
> > +				struct device_attribute *attr, char *buf)
> > +{
> > +	struct acpi_device *adev = to_acpi_device(dev);
> > +	int state;
> > +	int ret;
> > +
> > +	ret = acpi_device_get_power(adev, &state);
> > +	if (ret)
> > +		return ret;
> > +
> > +	return sprintf(buf, "%s %s\n", acpi_power_state_string(state),
> > +		       acpi_power_state_string(adev->power.state));
> > +}
> 
> You are showing 2 different things here in a single sysfs file, which is
> really frowned apon.  Any chance to split this up into two different
> sysfs files instead?

Well, I can, but I'm not sure how to call the other one.  "sw_power_state"
perhaps?

Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.