Subject: kern/24957: clcs(4) emits "AC97 read fail" errors
To: None <>
From: Lubomir Sedlacik <>
List: netbsd-bugs
Date: 03/29/2004 10:51:36
>Number:         24957
>Category:       kern
>Synopsis:       clcs(4) emits "AC97 read fail" errors on IBM ThinkPad T22
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Mar 29 08:52:00 UTC 2004
>Originator:     Lubomir Sedlacik
>Release:        NetBSD 1.6ZL
System: NetBSD krowak 1.6ZL NetBSD 1.6ZL (KROWAK-ACPI) #1: Fri Mar 26 19:17:10 CET 2004  salo@krowak:/opt/obj/sys/arch/i386/compile/KROWAK-ACPI i386
Architecture: i386
Machine: i386
Model: IBM ThinkPad T22
after upgrade to more recent -current (from Feb 2 to Mar 26) clcs(4) is
randomly emitting errors:

clcs0: AC97 read fail (VSTS==0) for add=0x2
clcs0: AC97 read fail (VSTS==0) for add=0x2

the "add" field can have different values.

the sound is distorted and unhearable, even with a patch from kern/12843,
until rebooted (sometimes more than once).

the only suspicious update i can think of in that timeframe seems to be new
ACPI-CA import, but it's just a wild guess.
install recent -current kernel to an IBM ThinkPad T22, sometimes see kernel
emit AC97 related errors from clcs(4) driver.
as a workaround, it usually seems to be gone after reboot