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From: Yi Yang <yi.y.yang@intel.com>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: David Brownell <david-b@pacbell.net>,
	pavel@ucw.cz, linux-pm@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org
Subject: Re: [linux-pm][PATCH] base: Change power/wakeup output from "" to  "unsupported" if wakeup feature isn't supported by a device
Date: Mon, 07 Jan 2008 10:05:45 +0800	[thread overview]
Message-ID: <1199671545.3551.16.camel@yangyi-dev.bj.intel.com> (raw)
In-Reply-To: <200801070257.58884.rjw@sisk.pl>

On Mon, 2008-01-07 at 02:57 +0100, Rafael J. Wysocki wrote:
> On Monday, 7 of January 2008, Yi Yang wrote:
> > On Fri, 2008-01-04 at 08:09 -0800, David Brownell wrote:
> > > > > This patch changes empty output to "unsupported" in order that a user knows
> > > > > wakeup feature isn't supported by this device when he/she
> > > > > 'cat /sys/devices/.../power/wakeup', please consider to apply,
> > > > > thanks.
> > > >
> > > > What about simply removing "wakuep" file if wakeup is not supported?
> > > 
> > > It may not *stay* unsupported, so I think changing it in either
> > > of those permanent ways would be confusing/misleading.
> > > 
> > > For example, USB devices have multiple states ... minimally, an
> > > unconfigured state, and a configured state.  Some have multiple
> > > configurations.  Only configured states can be wakeup-capable.
> > > So a given device might have three states, but support wakeup
> > > except in one of them...
> > If so, we can change "unsupported" to "unconfigurable" or "inoperable"
> > which can cover the states "unconfigured", "unsupported" and other
> > unknown states. :-).
> 
> The main problem with your patch is that is changes a documented behavior
> visible by the user space.  That should be done very cautiously.
Which applications are using this interface? if they assume "\n" means
the unconfigurable or unavailable state, this is very fragile.
> 
> Thanks,
> Rafael


  reply	other threads:[~2008-01-07  2:21 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-04 10:10 Yi Yang
2008-01-04 11:48 ` Pavel Machek
2008-01-04 16:09   ` David Brownell
2008-01-04 16:38     ` Alan Stern
2008-01-04 16:52       ` Olivier Galibert
2008-01-04 17:20         ` Oliver Neukum
2008-01-07  2:00           ` Yi Yang
2008-01-07  1:55         ` Yi Yang
2008-01-07  3:49           ` David Brownell
2008-01-07  1:52       ` Yi Yang
2008-01-07  1:37     ` Yi Yang
2008-01-07  1:57       ` Rafael J. Wysocki
2008-01-07  2:05         ` Yi Yang [this message]
2008-01-07 16:46           ` Rafael J. Wysocki
2008-01-07  1:21   ` Yi Yang
2008-01-04 16:31 ` David Brownell
2008-01-07  1:51   ` Yi Yang
2008-01-22 23:05 ` [PATCH 2.6.24-rc8] cpufreq: fix obvious condition statement error Yi Yang
2008-01-28 23:14   ` [PATCH 2.6.24] x86: add sysfs interface for cpuid module Yi Yang
2008-01-29  8:44     ` Sam Ravnborg
2008-01-29 22:22       ` Yi Yang
2008-01-30  7:48         ` Sam Ravnborg
2008-01-29 15:51     ` H. Peter Anvin
2008-01-29 17:52       ` Yi Yang
2008-01-30  6:09         ` H. Peter Anvin
2008-01-29 21:56       ` Yi Yang
2008-01-30  7:17         ` H. Peter Anvin
2008-01-29 22:13           ` Yi Yang
2008-01-30  7:33             ` H. Peter Anvin
2008-01-29 23:41     ` [RFC PATCH 2.6.24] x86: add sysfs interface for cpuid module, try 2 Yi Yang
2008-01-30 17:35       ` H. Peter Anvin
2008-01-31  1:18       ` [PATCH 2.6.24] Add new string functions real_strtoul and change kernel params to use them Yi Yang
2008-01-31 17:03         ` Randy Dunlap
2008-01-31 16:30           ` Yi Yang
2008-02-01  2:47             ` Randy Dunlap
2008-01-31 22:11         ` [PATCH 2.6.24] Add new string functions strict_strto* and convert kernel params to use them, take 2 Yi Yang
2008-02-01  0:02           ` [PATCH 2.6.24] Add new string functions strict_strto* and convert kernel params to use them, take 3 Yi Yang
2008-02-01  7:36           ` [PATCH 2.6.24] Add new string functions strict_strto* and convert kernel params to use them, take 2 Andrew Morton
2008-02-01  7:39           ` Andrew Morton
2008-02-01  7:40           ` Andrew Morton
2008-02-01 16:31     ` [PATCH 2.6.24] x86: add sysfs interface for cpuid module dean gaudet
2008-02-01 17:56       ` H. Peter Anvin
2008-02-01 17:58         ` H. Peter Anvin
2008-02-14 23:44   ` [PATCH 2.6.25-rc1] cpufreq: fix cpufreq policy refcount imbalance Yi Yang
2008-02-14 23:48   ` Yi Yang
2008-02-15 15:52     ` [linux-pm] " Alan Stern
2008-02-15 18:24       ` Greg KH
2008-02-15 21:01     ` Greg KH
2008-02-25  0:46     ` [PATCH 2.6.25-rc3] cpuidle: fix cpuidle time and usage overflow Yi Yang
2008-02-25 10:15       ` Ingo Molnar
2008-02-25  1:10         ` Yi Yang
2008-03-26  4:46       ` Len Brown

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