Sound misfunctions with kernel 2.6.15-26-386 on Jetway MB

Binary package hint: kernel-image-2.6.15-26-386-di

I am running Dapper on a system with a Jetway 625EMP800 motherboard with a VIA chipset and CPU (more details below on the hardware). I upgraded on 11 July (apt-get) and developed sound problems on installing the 2.6.15-26-386 kernel. The logon sound when the logon screen appears kept repeating, and the sound after logging on, and all other sounds did also. I just found a 'cure' - revert to the previous kernel - 2.6.15-25-386 - and the problem goes away. (The logon sound I had chose was a short 'thump' and the bug results in a repeated thump-thump-thump- ... sound).

My initial workaround was to remove my login from the audio group - then I'd get the problem while the login screen was up, but sound was disabled after I logged in, which was ok if I didn't need audio. Since I did want sound, this was a serious problem!

CPU info:
root@trippy:/proc# cat cpuinfo
processor : 0
vendor_id : CentaurHauls
cpu family : 6
model : 7
model name : VIA Samuel 2
stepping : 3
cpu MHz : 799.143
cache size : 64 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu de tsc msr cx8 mtrr pge mmx 3dnow
bogomips : 1600.02

THIS IS WITH THE OLDER 2.6.15-25-386 KERNEL:
root@trippy:/proc# lsmod
Module Size Used by
rfcomm 40216 0
l2cap 26244 5 rfcomm
bluetooth 49892 4 rfcomm,l2cap
ppdev 9220 0
via 47840 1
drm 73236 2 via
cpufreq_userspace 4696 0
cpufreq_stats 5636 0
freq_table 4740 1 cpufreq_stats
cpufreq_powersave 1920 0
cpufreq_ondemand 6428 0
cpufreq_conservative 7332 0
video 16260 0
tc1100_wmi 6916 0
sony_acpi 5644 0
pcc_acpi 12416 0
hotkey 11556 0
dev_acpi 11140 0
container 4608 0
button 6672 0
acpi_sbs 19980 0
battery 9988 1 acpi_sbs
ac 5252 1 acpi_sbs
i2c_acpi_ec 5120 1 acpi_sbs
dm_mod 58936 1
ipv6 265728 17
md_mod 72532 0
lp 11844 0
tsdev 8000 0
snd_seq_dummy 3844 0
snd_seq_oss 33536 0
snd_seq_midi 9376 0
snd_seq_midi_event 7552 2 snd_seq_oss,snd_seq_midi
snd_seq 51984 6 snd_seq_dummy,snd_seq_oss,snd_seq_midi,snd_seq_midi_event
i2c_viapro 8980 0
i2c_core 21904 2 i2c_acpi_ec,i2c_viapro
parport_pc 35780 1
parport 36296 3 ppdev,lp,parport_pc
rtc 13492 0
snd_via82xx 28824 2
snd_ac97_codec 92704 1 snd_via82xx
snd_ac97_bus 2304 1 snd_ac97_codec
analog 12320 0
snd_pcm_oss 53664 0
snd_mixer_oss 18688 1 snd_pcm_oss
gameport 15496 2 snd_via82xx,analog
8139cp 22528 0
ide_floppy 19328 0
snd_pcm 89864 4 snd_via82xx,snd_ac97_codec,snd_pcm_oss
snd_timer 25220 2 snd_seq,snd_pcm
snd_page_alloc 10632 2 snd_via82xx,snd_pcm
snd_mpu401_uart 7808 1 snd_via82xx
snd_rawmidi 25504 2 snd_seq_midi,snd_mpu401_uart
snd_seq_device 8716 5 snd_seq_dummy,snd_seq_oss,snd_seq_midi,snd_seq,snd_rawmidi
pcspkr 2180 0
floppy 62148 0
via_ircc 26900 0
irda 187068 1 via_ircc
psmouse 36100 0
crc_ccitt 2304 1 irda
serio_raw 7300 0
snd 55268 14 snd_seq_oss,snd_seq,snd_via82xx,snd_ac97_codec,snd_pcm_oss,snd_mixer_oss,snd_pcm,snd_timer,snd_mpu401_uart,snd_rawmidi,snd_seq_device
soundcore 10208 1 snd
8139too 26880 0
via_agp 9856 1
agpgart 34888 2 drm,via_agp
sis900 22912 0
mii 5888 3 8139cp,8139too,sis900
shpchp 45632 0
pci_hotplug 29236 1 shpchp
evdev 9856 1
ext3 135688 3
jbd 58772 1 ext3
ide_generic 1536 0
ehci_hcd 34184 0
uhci_hcd 33680 0
usbcore 130692 3 ehci_hcd,uhci_hcd
ide_cd 33028 0
cdrom 38560 1 ide_cd
ide_disk 17664 5
via82cxxx 9988 0 [permanent]
generic 5124 0
thermal 13576 0
processor 23360 1 thermal
fan 4868 0
capability 5000 0
commoncap 7296 1 capability
vga16fb 13704 1
vgastate 10368 1 vga16fb
fbcon 42784 72
tileblit 2816 1 fbcon
font 8320 1 fbcon
bitblit 6272 1 fbcon
softcursor 2304 1 bitblit
root@trippy:/proc#

I can run further tests with both kernels if necessary to track this down.

I also had a similar problem with the screensaver - when active, it appeared to freeze the system - I'll investigate that further and see if there's a relationship. There was already a screensaver problem with the earlier kernel.