From: Bing Zhao <bzhao@marvell.com>
To: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>,
	Andrey Yurovsky <andrey@cozybit.com>
CC: Dan Williams <dcbw@redhat.com>,
	Amitkumar Karwar <akarwar@marvell.com>,
	"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
	"libertas-dev@lists.infradead.org" <libertas-dev@lists.infradead.org>
Date: Thu, 17 Sep 2009 18:47:58 -0700
Subject: RE: [PATCH] libertas: Add auto deep sleep support for
 SD8385/SD8686/SD8688
Message-ID: <477F20668A386D41ADCC57781B1F704306DB9D021C@SC-VEXCH1.marvell.com>
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Hi Sebastian,

> -----Original Message-----
> From: Sebastian Andrzej Siewior [mailto:sebastian@breakpoint.cc]
> Sent: Thursday, September 17, 2009 9:12 AM
> To: Andrey Yurovsky
> Cc: Bing Zhao; Dan Williams; Amitkumar Karwar; linux-wireless@vger.kernel.org; libertas-
> dev@lists.infradead.org
> Subject: Re: [PATCH] libertas: Add auto deep sleep support for SD8385/SD8686/SD8688
> 
> * Andrey Yurovsky | 2009-09-16 13:47:48 [-0700]:
> 
> >> Some information (such as the interface name and path) in README file is out of date. We just
> copy-and-paste it for the new deepsleep command. We need a separate patch to clean up the REAME file
> and keep it up to date.
> >
> >Ok.  Either way, this is another out-of-band interface (regardless of
> >if it's debugfs or sysfs).  That said, I believe that debugfs should
> >be used for debugging, not for configuring driver/device features like
> >these.
> I agree on this. Debugfs is for debug only and should stay that way.
> What do other driver in regard to this? I hardly belive that the
> libertas driver is the only "deep sleep" user.

The debugfs interface has already been used for configuring some other parameters in libertas driver.
Choosing a different way for deep sleep configuration doesn't make sense to me.

> 
> >>> Deep sleep seems to pretty much "turn off" the wifi card (as far as
> >>> the user is concerned) so how about a simpler approach: enter deep
> >>> sleep when the interface is brought down (ifconfig wlanN down) and
> >>> exit deep sleep when it's brought up. ?Do this only when deep sleep is
> >>> supported/possible. ?Alternately, maybe this belongs as an rfkill
> >>> feature?
> >>
> >> Entering/exiting deep sleep doesn't have to depend on wlanN interface's up and down. User can
> still put the chip into sleep when wlanN is up. And, with auto deep sleep feature, the driver
> automatically wakes the chip up for sending user commands (for example, scan) and put the chip back
> to sleep after certain time period of inactivity. The deepsleep command through debugfs interface
> provides the flexibility of deep sleep options.
> >>
> >> The rfkill shuts down the RF transmitter of the device but most of other modules may be still
> functioning. The deep sleep shuts down most of the modules (including the RF) on the chip to save as
> much power as possible.
> >
> >It seems that when the device is in deep sleep, it's effectively
> >"turned off" as far as the user is concerned.  That seems really
> >similar to "ifconfig down" or rfkill, does the user really care about
> >anything beyond that?  I understand that it's possible to control this
> >feature independently of either of those functions, but is it ever
> >necessary?  If not, it would be great to just integrate it into one
> >(or both) of these already standard network interface semantics and
> >not introduce a whole new configuration parameter.
> 
> iwconfig has an interface for this I think:
> |interface power {period N|timeout N|saving N|off}
> 
> From what I see in the man page it covers pretty much what you wrote in
> the Readme file. So it looks like like there is your flexible interface
> you've been looking for :)

Unfortunately, the "iwconfig wlanN power" command is used for ieee power saving mode in the driver.

Regards,

Bing

> 
> >  -Andrey
> >
> >> Regards,
> >>
> >> Bing
> 
> Sebastian