[PATCH] x86-64: Disable local APIC timer use on AMD systems with C1E

AMD dual core laptops with C1E do not run the APIC timer correctly
when they go idle. Previously the code assumed this only happened
on C2 or deeper.  But not all of these systems report support C2.

Use a AMD supplied snippet to detect C1E being enabled and then disable
local apic timer use.

This supercedes an earlier workaround using DMI detection of specific systems.

Thanks to Mark Langsdorf for the detection snippet.

Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 3 insertions, 29 deletions

diff --git a/arch/i386/kernel/apic.c b/arch/i386/kernel/apic.c
index e88415282a6f..93aa911646ad 100644
--- a/arch/i386/kernel/apic.c
+++ b/arch/i386/kernel/apic.c
@@ -272,32 +272,6 @@ static void __devinit setup_APIC_timer(void)
 }
 
 /*
- * Detect systems with known broken BIOS implementations
- */
-static int __init lapic_check_broken_bios(struct dmi_system_id *d)
-{
-	printk(KERN_NOTICE "%s detected: disabling lapic timer.\n",
-		       d->ident);
-	local_apic_timer_disabled = 1;
-	return 0;
-}
-
-static struct dmi_system_id __initdata broken_bios_dmi_table[] = {
-	{
-		/*
-		 * BIOS exports only C1 state, but uses deeper power
-		 * modes behind the kernels back.
-		 */
-		  .callback = lapic_check_broken_bios,
-		  .ident = "HP nx6325",
-		  .matches = {
-			DMI_MATCH(DMI_PRODUCT_NAME, "HP Compaq nx6325"),
-		  },
-	 },
-	 {}
-};
-
-/*
  * In this functions we calibrate APIC bus clocks to the external timer.
  *
  * We want to do the calibration only once since we want to have local timer
@@ -372,12 +346,12 @@ void __init setup_boot_APIC_clock(void)
 	long delta, deltapm;
 	int pm_referenced = 0;
 
-	/* Detect know broken systems */
-	dmi_check_system(broken_bios_dmi_table);
+	if (boot_cpu_has(X86_FEATURE_LAPIC_TIMER_BROKEN))
+		local_apic_timer_disabled = 1;
 
 	/*
 	 * The local apic timer can be disabled via the kernel
-	 * commandline or from the dmi quirk above. Register the lapic
+	 * commandline or from the test above. Register the lapic
 	 * timer as a dummy clock event source on SMP systems, so the
 	 * broadcast mechanism is used. On UP systems simply ignore it.
 	 */