Commit a2ef3a50 authored by Andy Currid's avatar Andy Currid Committed by Linus Torvalds
Browse files

[PATCH] Fix HPET operation on 64-bit NVIDIA platforms

From: "Andy Currid" <>

This patch fixes a kernel panic during boot that occurs on NVIDIA platforms
that have HPET enabled.

When HPET is enabled, the standard timer IRQ is routed to IOAPIC pin 2 and is
advertised as such in the ACPI APIC table - but an earlier workaround in the
kernel was ignoring this override.  The fix is to honor timer IRQ overrides
from ACPI when HPET is detected on an NVIDIA platform.
Signed-off-by: default avatarAndy Currid <>
Cc: "Brown, Len" <>
Cc: "Yu, Luming" <>
Cc: Andi Kleen <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent d44647b0
......@@ -271,6 +271,18 @@ __setup("enable_8254_timer", setup_enable_8254_timer);
#include <linux/pci_ids.h>
#include <linux/pci.h>
static int nvidia_hpet_detected __initdata;
static int __init nvidia_hpet_check(unsigned long phys, unsigned long size)
nvidia_hpet_detected = 1;
return 0;
/* Temporary Hack. Nvidia and VIA boards currently only work with IO-APIC
off. Check for an Nvidia or VIA PCI bridge and turn it off.
Use pci direct infrastructure because this runs before the PCI subsystem.
......@@ -317,11 +329,19 @@ void __init check_ioapic(void)
/* All timer overrides on Nvidia
seem to be wrong. Skip them. */
acpi_skip_timer_override = 1;
"Nvidia board detected. Ignoring ACPI timer override.\n");
* All timer overrides on Nvidia are
* wrong unless HPET is enabled.
nvidia_hpet_detected = 0;
if (nvidia_hpet_detected == 0) {
acpi_skip_timer_override = 1;
printk(KERN_INFO "Nvidia board "
"detected. Ignoring ACPI "
"timer override.\n");
/* RED-PEN skip them on mptables too? */
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