linux-kernel - Re: [GIT PATCH] USB autosuspend fixes for 2.6.23-rc6

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Message-ID: <20070913145207.GF3563@stusta.de>
Date:	Thu, 13 Sep 2007 16:52:07 +0200
From:	Adrian Bunk <bunk@...nel.org>
To:	Greg KH <gregkh@...e.de>
Cc:	Linus Torvalds <torvalds@...l.org>, Andrew Morton <akpm@...l.org>,
	linux-kernel@...r.kernel.org,
	linux-usb-devel@...ts.sourceforge.net,
	Alan Stern <stern@...land.harvard.edu>,
	Oliver Neukum <oneukum@...e.de>
Subject: Re: [GIT PATCH] USB autosuspend fixes for 2.6.23-rc6

On Thu, Sep 13, 2007 at 06:33:21AM -0700, Greg KH wrote:
> It turns out that USB devices suck when it comes to powermanagement
> issues :(
> 
> A number of patches have been submitted near the end of this kernel
> release cycle that add new device ids to the quirk table in the kernel
> to disable autosuspend for specific devices.  However, a number of
> developers are very worried that even with the testing that has been
> done, once 2.6.23 is released, we are going to get a whole raft of angry
> users when their devices break in nasty ways.
> 
> As an example, it seems that almost 2/3 of all USB printers just can not
> handle autosuspend.  And there's a _lot_ of USB printers out there...
> 
> When researching how other operating systems handle this, it was found
> out that they use a whitelist of devices that are able to properly
> suspend.  So, in the future, that is how we are going to handle this.
> 
> These two patches address the need today to have users machines still
> work, even if they might draw more power than they possibly could (which
> is not any more than they did in 2.6.22.)
> 
> These patches do two things:
>   - disable USB autosuspend on all devices except for USB hubs.  This
>     can be easily overridden by userspace to turn on autosuspend for
>     devices that a user wants to.  HAL will use a whitelist in the
>     future for these types of devices.
>...

Not related to the patch for 2.6.23, but I have a gut feeling that 
something might be done the wrong way later:

If I understand you correctly, you are saying that I will have to 
install HAL for getting a whitelist for in-kernel functionality?

It is a good thing if userspace can add currently missing devices to
whitelists, but the whitelist itself should be in the kernel.

> thanks,
> 
> greg k-h
>...

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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