vga switcheroo not working / crashing the machine on i915/nvidia hybrid. (ASUS U30JC)

[Giacomo]

Hello.

In my double-carded ASUS U30JC (nvidia + intel i915) I do the following:

stop X

This is the output of /sys/kernel/debug/vgaswitcheroo/switch

daphne linux # cat /sys/kernel/debug/vgaswitcheroo/switch
0: :Pwr:0000:01:00.0
1:+:Pwr:0000:00:02.0 (intel graphic card in use, ok)

echo "DDIS" > /sys/kernel/debug/vgaswitcheroo/switch does not change
the output above (intel remains marked as active)

echo "OFF" > /sys/kernel/debug/vgaswitcheroo/switch

seems to switch off Nvidia card, because the output above becomes:
0: :Off:0000:01:00.0
1:+:Pwr:0000:00:02.0

restarting X completely freezes the machine, black screen (need to power down
by
pressing the power button).


ASUS U30JC Nvidia (nouveau) + intel i915.

Kernel 2.6.35
x11-base/xorg-server 1.9.2.902
x11-drivers/xf86-video-nouveau 0.0.16_pre20101010

Shutting down the Nvidia graphic card via acpi_call
https://github.com/mkottman/acpi_call
produces the same freeze after trying to restart X.

Same problem with kernel 2.6.36 and acpi_call.
Did not try vga switcheroo on 2.6.36 due to problems with that kernel

https://bugzilla.kernel.org/show_bug.cgi?id=24542

echo "OFF" > /sys/kernel/debug/vgaswitcheroo/switch

produces in dmesg:

Dec  8 00:06:18 daphne kernel: VGA switcheroo: switched nouveau off
Dec  8 00:06:18 daphne kernel: [drm] nouveau 0000:01:00.0: Disabling fbcon
acceleration...
Dec  8 00:06:18 daphne kernel: [drm] nouveau 0000:01:00.0: Unpinning
framebuffer(s)...
Dec  8 00:06:18 daphne kernel: [drm] nouveau 0000:01:00.0: Evicting buffers...
Dec  8 00:06:18 daphne kernel: [drm] nouveau 0000:01:00.0: Idling channels...
Dec  8 00:06:18 daphne kernel: [drm] nouveau 0000:01:00.0: Suspending GPU
objects...
Dec  8 00:06:19 daphne kernel: [drm] nouveau 0000:01:00.0: And we're gone!
Dec  8 00:06:19 daphne kernel: nouveau 0000:01:00.0: PCI INT A disabled
Dec  8 00:06:19 daphne kernel: nouveau 0000:01:00.0: power state changed by
ACPI to D3

which seems to be correct.

The crash taking place when restarting X does not leave any trace on dmesg.

Thanks in advance.

Giacomo.
Elettra Synchrotron Radiation Facility
Trieste, IT.

-- 
Giacomo S.
http://www.giacomos.it

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