linux-kernel - Re: usb autosuspend is history after S2R (also on 2.6.31; UVC?)

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Date:	Wed, 16 Sep 2009 20:19:10 +0200
From:	Andreas Mohr <andi@...as.de>
To:	Oliver Neukum <oliver@...kum.org>
Cc:	Andreas Mohr <andi@...as.de>,
	Alan Stern <stern@...land.harvard.edu>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	laurent.pinchart@...net.be, Matthew Garrett <mjg59@...f.ucam.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: usb autosuspend is history after S2R (also on 2.6.31; UVC?)

Hi,

On Tue, Sep 15, 2009 at 09:48:28PM +0200, Oliver Neukum wrote:
> Am Dienstag, 15. September 2009 20:51:45 schrieb Andreas Mohr:
> 
> > So, does the uvc driver need a bit of handholding here?
> > It likely shouldn't simply forget about its autosuspend status after
> > resume...
> 
> Can you please provide what you get when you read the "level" file
> of the device's power directory?

After boot:

# cat 5-5/product
Acer Crystal Eye webcam
# cat 5-5/power/level
on

After re-enabling disabled /etc/rc.local autosuspend tweaks:

# cat 5-5/power/level
auto

> Secondly, please verify, that it works before the STR cycle and post

It does:

Recent USB suspend statistics
Active  Device name
  0.0%  USB device  5-5 : Acer Crystal Eye webcam (SuYin)
  0.0%  USB device usb5 : EHCI Host Controller (Linux 2.6.31 ehci_hcd)
  0.0%  USB device usb4 : UHCI Host Controller (Linux 2.6.31 uhci_hcd)
  0.0%  USB device usb3 : UHCI Host Controller (Linux 2.6.31 uhci_hcd)
  0.0%  USB device usb2 : UHCI Host Controller (Linux 2.6.31 uhci_hcd)
  0.0%  USB device usb1 : UHCI Host Controller (Linux 2.6.31 uhci_hcd)

> a syslog of a suspend/resume cycle with CONFIG_USB_DEBUG and
> only this device attached if possible. Thirdly, please verify that only
> uvc is affected.

Hmmmm...

I just did the first S2R after boot, and the result is this:

Recent USB suspend statistics
Active  Device name          
  0.0%  USB device  5-5 : Acer Crystal Eye webcam (SuYin)
  0.0%  USB device usb5 : EHCI Host Controller (Linux 2.6.31 ehci_hcd)
  0.0%  USB device usb4 : UHCI Host Controller (Linux 2.6.31 uhci_hcd)
  0.0%  USB device usb3 : UHCI Host Controller (Linux 2.6.31 uhci_hcd)
  0.0%  USB device usb2 : UHCI Host Controller (Linux 2.6.31 uhci_hcd)
  0.0%  USB device usb1 : UHCI Host Controller (Linux 2.6.31 uhci_hcd)
# cat 5-5/power/level           
auto

Weird. Either it was always working and I'm just _very_ wrong,
or it's erratic and gets reset every couple S2Rs only.

Anyway, doesn't change the fact that the r8169 WOL PHY setting is toast
after every S2R as well ;)
# ethtool -s eth0 wol d
# ethtool eth0
...
        Wake-on: d
...

which then reverts to
# ethtool eth0
...
        Wake-on: g
...
thus wasting a wee bit of power(, too).

> > Or would Matthew's uvc autosuspend patch
> > http://osdir.com/ml/fedora-extras-commits/2009-07/msg06079.html
> > help here?
> 
> Please test it. It shouldn't work, but if it works there's a fundamental
> flaw.

Hmm, rebuild (of patch plus CONFIG_USB_DEBUG) would take >> 2 hours,
will have to wait until later.

Thanks,

Andreas
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