problems with suspend-to-disk and rivafb (NV32) on ppc

Hi alltogether!

On the debian-powerpc and linuxppc-dev lists from time to time pops up a
subject which probably better belongs on this list since it discusses a
problem with the nvidia graphics card used in newer 12" powerbooks. It seems
it only occurs on graphics adapters with NV32 chips and newer.
Also, I did not have the problem with kernels up to 2.6.10 together with
the patch from Guido Günther providing suspend-to-disk. It  seeems  the
problem appeared after 2.6.11 with the merge of swsusp2. To get
better data I could test the old kernels, but perhaps the following
description of the problem rings a bell to someone:

boot, suspend-to-disk from X -> crashes in the first state of suspend 
      when switching to another vt
boot, switch from X to vt[1-6], suspend-to-disk -> works
      suspend-resume to/from disk works from now on under X too 
boot, switch from X to vt8 (not allocated in inittab) -> crash

summary: directly after boot the system crashes on chvt to an to that
time unused vt.
Probably related:
If I start mol (Mac-on-Linux) the system crashes even when I try to
switch to vt1. This also means that I cannot use fullscreen mol on tty8.
Most interesting however is that I can still type "halt" or
"/etc/init.d/gdm stop" in my xterm and the machine kills X and shuts
down normally, even after running mol. I can suspend to disk "normally"
again. To me this looks as if the machine follows different code paths
in the kernel in each situation and some of them are save, others are
not.

Please tell me what I can do to debug this further, I am also more than
willing to test patches.

With best regards,

Wolfi



relevant part of lspci -v:
0000:00:10.0 VGA compatible controller: nVidia Corporation NV34M [GeForce FX Go5200] (rev a1) (prog-if 00 [VGA])
        Subsystem: nVidia Corporation: Unknown device 0010
        Flags: bus master, 66MHz, medium devsel, latency 248, IRQ 48
        Memory at 91000000 (32-bit, non-prefetchable) [size=16M]
        Memory at a0000000 (32-bit, prefetchable) [size=128M]
        Expansion ROM at 90000000 [disabled] [size=128K]
        Capabilities: [60] Power Management version 2
        Capabilities: [44] AGP version 3.0


cat /proc/cpuinfo:
processor	: 0
cpu		: 7447/7457, altivec supported
clock		: 765MHz
revision	: 0.1 (pvr 8002 0101)
bogomips	: 508.92
machine		: PowerBook6,2
motherboard	: PowerBook6,2 MacRISC3 Power Macintosh
detected as	: 287 (PowerBook G4)
pmac flags	: 0000001a
L2 cache	: 512K unified
memory		: 384MB
pmac-generation	: NewWorld


My xorg.conf:

Section "Files"
	FontPath	"unix/:7100"			# local font server
	# if the local font server has problems, we can fall back on these
	FontPath	"/usr/lib/X11/fonts/Type1"
	FontPath	"/usr/lib/X11/fonts/CID"
	FontPath	"/usr/lib/X11/fonts/Speedo"
	FontPath	"/usr/lib/X11/fonts/misc"
	FontPath	"/usr/lib/X11/fonts/cyrillic"
	FontPath	"/usr/lib/X11/fonts/100dpi"
	FontPath	"/usr/lib/X11/fonts/75dpi"
	FontPath	"/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
	FontPath	"/var/lib/defoma/x-ttcidfont-conf.d/dirs/CID"
EndSection

Section "Module"
	Load	"GLcore"
	Load	"bitmap"
	Load	"dbe"
	Load	"ddc"
	Load	"dri"
	Load	"extmod"
	Load	"freetype"
	Load	"glx"
	Load	"int10"
	Load	"record"
	Load	"speedo"
	Load	"type1"
	Load	"vbe"
	Load	"xtt"
EndSection

Section "InputDevice"
	Identifier	"Generic Keyboard"
	Driver		"keyboard"
	Option		"CoreKeyboard"
	Option		"XkbRules"	"xfree86"
	Option		"XkbModel"	"macintosh"
	Option		"XkbLayout"	"us"
EndSection

Section "InputDevice"
	Identifier	"Configured Mouse"
	Driver		"mouse"
	Option		"CorePointer"
	Option		"Device"		"/dev/input/mice"
	Option		"Protocol"		"ImPS/2"
	Option		"Emulate3Buttons"	"false"
	Option		"ZAxisMapping"		"4 5"
	Option		"Buttons"		"5"
EndSection

Section "Device"
	Identifier	"Generic Video Card"
	Driver		"nv"
	BusID		"PCI:0:16:0"
	Option 		"UseFBDev"		"false"
	Option		"CrtcNumber"		"1"
	Option		"BackingStore"		"true"
EndSection

Section "Monitor"
	Identifier	"Generic Monitor"
	HorizSync	28-49
	VertRefresh	43-72
	Option		"DPMS"
EndSection

Section "Screen"
	Identifier	"Default Screen"
	Device		"Generic Video Card"
	Monitor		"Generic Monitor"
	DefaultDepth	24
	SubSection "Display"
		Depth		24
		Modes		"1024x768" "800x600" "640x480"
	EndSubSection
EndSection

Section "ServerLayout"
	Identifier	"Default Layout"
	Screen		"Default Screen"
	InputDevice	"Generic Keyboard"
	InputDevice	"Configured Mouse"
EndSection

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