Bug 3551

Summary:	disable ACPI timer override on Nvidia i386
Product:	ACPI	Reporter:	Andi Kleen (andi-bz)
Component:	Config-Interrupts	Assignee:	Len Brown (lenb)
Status:	CLOSED CODE_FIX
Severity:	high	CC:	acpi-bugzilla
Priority:	P2
Hardware:	i386
OS:	Linux
Kernel Version:	2.6.9rc3	Subsystem:
Regression:	---	Bisected commit-id:
Attachments:	Disable timer override on Nvidia New version of nvidia timer override workaround cleanup patch to add to previous

Description Andi Kleen 2004-10-11 06:13:27 UTC

After some discussion with Nvidia people it turns out all Timer Overrides
on Nvidia boards are wrong. They cause random failures with IO-APIC on.
According to Nvidia this should also be safe for future chipsets of theirs.

x86-64 already has a similar patch queued for 2.6.10pre. On i386 it is 
more critical however because x86-64 previously turned off the IO-APIC
on these boxes. On i386 it depends on the .config

Comment 1 Andi Kleen 2004-10-11 06:15:26 UTC

Created attachment 3806 [details]
Disable timer override on Nvidia


This patch adds an early pci scan that checks for this bridge and disables
the timer override for any nvidia board. Code ported from x86-64.

Some testing on a Nforce2 before submitting would be good.

Comment 2 Andi Kleen 2004-10-11 06:17:22 UTC

Created attachment 3807 [details]
New version of nvidia timer override workaround

Previous patch was missing two files.

Comment 3 Len Brown 2004-11-10 21:59:41 UTC

Patch looks good, but probably better w/o this line:

+               printk(KERN_INFO
+             "NForce bridge found, setting ACPI timer override\n");

because the BIOS may be correct and not supply an override,
in which case this workaround and this line are are NOP.

Plus, if we do find a bogus timer override, we already squawk about it:

        if (acpi_skip_timer_override &&
                intsrc->bus_irq == 0 && intsrc->global_irq == 2) {
                        printk(PREFIX "BIOS IRQ0 pin2 override ignored.\n");

I'll apply this patch, sans prink, to the ACPI test tree.

Comment 4 Len Brown 2004-11-11 00:32:11 UTC

Created attachment 4010 [details]
cleanup patch to add to previous

additional patch to delete now obsolete dmi-scan entries
and also fix the build when ACPI & !IOAPIC

Comment 5 Len Brown 2004-12-05 19:45:11 UTC

shipped in 2.6.10-rc3 
closing.