nm256: register strangeness related to lockups

[Christian Trefzer <ctrefzer@gmx.de>]

Hi folks,

in the process of analyzing the frequent crashes during the snd-nm256
module insertion I stumbled across the following register values
(reading 32bit words at a time in a loop with pcitweak):

--- nm256-crashes-sometimes	2006-03-26 15:27:32.873773008 +0200
+++ nm256-never-crashed-so-far	2006-03-26 15:27:42.669283864 +0200
@@ -5,7 +5,7 @@
 0x00000000
 0x00000000
 0x20010100
-0x22a0c0c0
+0xa2a0c0c0
 0xfef0fd00
 0xf9f0f800
 0x00000000

This would be in word #7 (starting from 0), 0010 0010 vs. 1010 0010. I
tried to write back the "safer" values to the chip, but reading them
back sometimes showed that the write had failed, probably due to the
registers being locked.

I'd very much like to do the "correction" in the driver itself, and
maybe have it tested on other laptops as well - I have only a Dell
Latitude CPiA (NM2200) for that purpose, and no other incarnation of the
neomagic chip at hand. Also, for starters it would be very interesting
to see similar dumps on other machines, to see if the difference between
working and hardlocking is the same.


Some lspci output for reference:

00:00.0 Host bridge: Intel Corporation 440BX/ZX/DX - 82443BX/ZX/DX Host bridge (rev 03)
00:01.0 PCI bridge: Intel Corporation 440BX/ZX/DX - 82443BX/ZX/DX AGP bridge (rev 03)
00:03.0 CardBus bridge: Texas Instruments PCI1225 (rev 01)
00:03.1 CardBus bridge: Texas Instruments PCI1225 (rev 01)
00:07.0 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ISA (rev 02)
00:07.1 IDE interface: Intel Corporation 82371AB/EB/MB PIIX4 IDE (rev 01)
00:07.2 USB Controller: Intel Corporation 82371AB/EB/MB PIIX4 USB (rev 01)
00:07.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 02)
01:00.0 VGA compatible controller: Neomagic Corporation NM2200 [MagicGraph 256AV] (rev 20)
01:00.1 Multimedia audio controller: Neomagic Corporation NM2200 [MagicMedia 256AV Audio] (rev 20)


01:00.0 0300: 10c8:0005 (rev 20)
	Subsystem: 1028:0088
	Flags: bus master, medium devsel, latency 32, IRQ 11
	Memory at f9000000 (32-bit, prefetchable) [size=16M]
	Memory at fdc00000 (32-bit, non-prefetchable) [size=4M]
	Memory at fdb00000 (32-bit, non-prefetchable) [size=1M]
	Capabilities: [dc] Power Management version 1
00: c8 10 05 00 07 00 90 02 20 00 00 03 00 20 80 00
10: 08 00 00 f9 00 00 c0 fd 00 00 b0 fd 00 00 00 00
20: 00 00 00 00 00 00 00 00 00 00 00 00 28 10 88 00
30: 00 00 00 00 dc 00 00 00 00 00 00 00 0b 01 10 ff
40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
d0: 00 00 00 00 00 00 00 00 00 00 00 00 01 00 21 06
e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

01:00.1 0401: 10c8:8005 (rev 20)
	Subsystem: 1028:0088
	Flags: medium devsel, IRQ 5
	Memory at f8c00000 (32-bit, prefetchable) [size=4M]
	Memory at fda00000 (32-bit, non-prefetchable) [size=1M]
	Capabilities: [dc] Power Management version 1
00: c8 10 05 80 02 00 90 02 20 00 01 04 00 00 80 00
10: 08 00 c0 f8 00 00 a0 fd 00 00 00 00 00 00 00 00
20: 00 00 00 00 00 00 00 00 00 00 00 00 28 10 88 00
30: 00 00 00 00 dc 00 00 00 00 00 00 00 05 02 00 00
40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
d0: 00 00 00 00 00 00 00 00 00 00 00 00 01 00 21 00
e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


(was taken while actually playing sound - guess I should take a dump
every time I am about to insert the module and look for differences...)

I am currently stuck here, so any hint would be appreciated : )


Kind regards,
Chris

Attachment: pgpTbpnfGRvZo.pgp
Description: PGP signature