[PATCH] Fix HPET operation on 32-bit NVIDIA platforms

From: "Andy Currid" <ACurrid@nvidia.com>

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: Andy Currid <acurrid@nvidia.com>
Cc: "Brown, Len" <len.brown@intel.com>
Cc: "Yu, Luming" <luming.yu@intel.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 20 insertions, 3 deletions

diff --git a/arch/i386/kernel/acpi/earlyquirk.c b/arch/i386/kernel/acpi/earlyquirk.c
index 2e3b643a4dc4..1649a175a206 100644
--- a/arch/i386/kernel/acpi/earlyquirk.c
+++ b/arch/i386/kernel/acpi/earlyquirk.c
@@ -5,17 +5,34 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/pci.h>
+#include <linux/acpi.h>
+
 #include <asm/pci-direct.h>
 #include <asm/acpi.h>
 #include <asm/apic.h>
 
+#ifdef CONFIG_ACPI
+
+static int nvidia_hpet_detected __initdata;
+
+static int __init nvidia_hpet_check(unsigned long phys, unsigned long size)
+{
+        nvidia_hpet_detected = 1;
+        return 0;
+}
+#endif
+
 static int __init check_bridge(int vendor, int device)
 {
 #ifdef CONFIG_ACPI
-        /* According to Nvidia all timer overrides are bogus. Just ignore
-           them all. */
+        /* According to Nvidia all timer overrides are bogus unless HPET
+           is enabled. */
         if (vendor == PCI_VENDOR_ID_NVIDIA) {
-                acpi_skip_timer_override = 1;
+                nvidia_hpet_detected = 0;
+                acpi_table_parse(ACPI_HPET, nvidia_hpet_check);
+                if (nvidia_hpet_detected == 0) {
+                        acpi_skip_timer_override = 1;
+                }
         }
 #endif
         if (vendor == PCI_VENDOR_ID_ATI && timer_over_8254 == 1) {