Bug 7789

Summary:	AMD64/ATI : timer is running twice as fast as it should
Product:	Platform Specific/Hardware	Reporter:	Timo Jyrinki (timo.jyrinki)
Component:	x86-64	Assignee:	Andi Kleen (andi-bz)
Status:	CLOSED CODE_FIX
Severity:	normal	CC:	bunk, hugh, rohlfing
Priority:	P2
Hardware:	i386
OS:	Linux
Kernel Version:	2.6.20-rc4	Subsystem:
Regression:	---	Bisected commit-id:
Attachments:	dmesg-2.6.19.log dmesg-2.6.20.log lspci -nvv output lspci -vv patch to revert the possible culprit dmesg-2.6.20-patched.log

Description Timo Jyrinki 2007-01-08 05:14:39 UTC

I'm creating a new bug as it was suggested in bug 3927. In 2.6.20, there is a
regression on at least my ATI board (and thus probably others) that the clock
runs at double speed. The most likely culprit is
http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=b026872601976f666bae77b609dc490d1834bf77

I will attach dmesg logs from 2.6.19 and 2.6.20-rc4, plus lspci outputs.

Note that the following lines are missing from 2.6.20 dmesg output:
[ 0.000000] ATI board detected. Disabling timer routing over 8254.
[ 31.368871] ..MP-BIOS bug: 8254 timer not connected to IO-APIC

Comment 1 Timo Jyrinki 2007-01-08 05:15:45 UTC

Created attachment 10028 [details]
dmesg-2.6.19.log

Comment 2 Timo Jyrinki 2007-01-08 05:16:22 UTC

Created attachment 10029 [details]
dmesg-2.6.20.log

Comment 3 Timo Jyrinki 2007-01-08 05:17:13 UTC

Created attachment 10030 [details]
lspci -nvv output

Comment 4 Timo Jyrinki 2007-01-08 05:18:21 UTC

Created attachment 10031 [details]
lspci -vv

Comment 5 Adrian Bunk 2007-01-08 12:14:51 UTC

Created attachment 10034 [details]
patch to revert the possible culprit

Does applying this patch fix the issue?

Comment 6 Timo Jyrinki 2007-01-08 13:43:58 UTC

Created attachment 10035 [details]
dmesg-2.6.20-patched.log

Confirming that using that revert patch fixes the issue and clock works
normally again.

ak's original git comment had "TBD Experimental. Needs a lot of testing", so if
it hasn't received that testing it'd probably be good to revert this. I'm happy
to test any future patches to the issue with my hardware.

Comment 7 Adrian Bunk 2007-01-08 19:02:10 UTC

The commit that broke it got reverted in Linus' tree.

Thanks for your bug report!

Comment 8 Timo Jyrinki 2007-01-11 08:32:00 UTC

post scriptum: the board is MSI RS482M4-ILD with the latest (and probably last)
BIOS version 1.2. I'm now trying to follow linux-kernel on possible 2.6.21
patches regarding this issue.