LVDS backlight doesn''t turn on after going into powersaving mode (dual-monitor)

[Diggory]

Binary package hint: xserver-xorg-video-nouveau

I'm using the following nouveau, explicitly enabled in xorg.conf.
ii libdrm-nouveau1 2.4.14-1ubuntu1 Userspace interface to nouveau-specific kernel DRM services -- r
ii nouveau-kernel-source 0.0.15+git20090823-0ubuntu1 DKMS source for the nouveau kernel modules
ii xserver-xorg-video-nouveau 1:0.0.10~git+20090823+569a17a-0ubuntu1 X.Org X server -- Nouveau display driver (experimental)

It works and supports xrandr display hotplugging (currently running LVDS 1680x1050 and VGA 1280x1024, enabled as a separate screen after kde loads).
Once the display back-light has turned off (power-saving), it doesn't turn on again properly on the LVDS screen (VGA screen is fine but I'm not sure the power saving even works on this one). To turn the backlight back on I can VT-switch and return to X, or set the backlight brightness via the kde power-management applet. If I use the keyboard Fn+.. brightness shortcuts (might be hardware shortcuts; using a T61) the backlight gets turned off again (can still just-about see content on the screen).

I was previously using the nvidia closed-source driver which worked fine (apart from lack of xrandr support...).

dmesg snippet, covering event:
---------------
[ 21.654584] iwlagn 0000:03:00.0: firmware: requesting iwlwifi-4965-2.ucode
[ 22.093205] usplash:401 freeing invalid memtype ffffffffd9000000-ffffffffd9e00000
[ 22.220657] iwlagn 0000:03:00.0: loaded firmware version 228.61.2.24
[ 22.436043] Registered led device: iwl-phy0::radio
[ 22.436066] Registered led device: iwl-phy0::assoc
[ 22.436083] Registered led device: iwl-phy0::RX
[ 22.436099] Registered led device: iwl-phy0::TX
[ 22.502128] ADDRCONF(NETDEV_UP): wlan0: link is not ready
[ 23.120996] e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: None
[ 23.121000] 0000:00:19.0: eth0: 10/100 speed: disabling TSO
[ 23.121458] ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 26.882951] [TTM] Zone kernel: Available graphics memory: 1996878 kiB.
[ 26.915241] mtrr: type mismatch for e0000000,10000000 old: write-back new: write-combining
[ 26.915499] nouveau 0000:01:00.0: Allocating FIFO number 1
[ 26.928959] nouveau 0000:01:00.0: nouveau_channel_alloc: initialised FIFO 1
[ 28.741008] nouveau 0000:01:00.0: Allocating FIFO number 2
[ 28.754074] nouveau 0000:01:00.0: nouveau_channel_alloc: initialised FIFO 2
[ 33.830054] eth0: no IPv6 routers present
[ 40.057791] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[ 40.057793] Bluetooth: BNEP filters: protocol multicast
[ 40.063268] Bridge firewalling registered
[ 40.386630] virbr0: starting userspace STP failed, starting kernel STP
[ 41.178349] lo: Disabled Privacy Extensions
[ 4454.732544] __ratelimit: 6 callbacks suppressed
[ 4454.732547] ACPI: EC: missing confirmations, switch off interrupt mode.
[11117.493444] npviewer.bin[15207]: segfault at ff99cd48 ip 00000000ff99cd48 sp 00000000ffb9f4cc error 14
[12240.409638] npviewer.bin[15728]: segfault at ff99cd48 ip 00000000ff99cd48 sp 00000000ff9649ac error 14
---------------

[Bryce Harrington (bryce)]

I've uploaded a newer -nouveau to Lucid which has a significant amount of changes since the version this bug is reported against. Possibly the issue is now resolved. Please test that and let us know if the issue still exists.

[Bryce Harrington (bryce)]

We're closing this bug since it is has been some time with no response from the original reporter. However, if the issue still exists please feel free to reopen with the requested information. Also, if you could, please test against the latest development version of Ubuntu, since this confirms the bug is one we may be able to pass upstream for help.

[Diggory (diggory-hardy)]

Sorry for the long delay in responding -- I was meaning to test this but didn't get around to it. I just tested it out and the backlight was reactivated coming out of standby mode. (Can't say I haven't found other issues with nouveau, but anyway.)