From ab68805955ee3dd84a6aa76cd70e61fde996968d Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Thu, 16 Feb 2006 23:42:04 +0100 Subject: [PATCH] [PATCH] x86_64: Don't enable ATI apicmaintimer workaround when the machine has C2 or C3 Many laptops have problems with ticking the local APIC timer in C2/C3. The code added earlier to use it by default on ATI didn't really work for them. Don't enable it when the system supports C2/C3. This doesn't fix the problem fully, but at least it's not worse than before. Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- arch/x86_64/kernel/io_apic.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/arch/x86_64/kernel/io_apic.c b/arch/x86_64/kernel/io_apic.c index 4282d72b2a2..2585c1d92b2 100644 --- a/arch/x86_64/kernel/io_apic.c +++ b/arch/x86_64/kernel/io_apic.c @@ -30,6 +30,9 @@ #include #include #include +#ifdef CONFIG_ACPI +#include +#endif #include #include @@ -260,6 +263,8 @@ __setup("apic", enable_ioapic_setup); And another hack to disable the IOMMU on VIA chipsets. + ... and others. Really should move this somewhere else. + Kludge-O-Rama. */ void __init check_ioapic(void) { @@ -307,6 +312,17 @@ void __init check_ioapic(void) case PCI_VENDOR_ID_ATI: if (apic_runs_main_timer != 0) break; +#ifdef CONFIG_ACPI + /* Don't do this for laptops right + right now because their timer + doesn't necessarily tick in C2/3 */ + if (acpi_fadt.revision >= 3 && + (acpi_fadt.plvl2_lat + acpi_fadt.plvl3_lat) < 1100) { + printk(KERN_INFO +"ATI board detected, but seems to be a laptop. Timer might be shakey, sorry\n"); + break; + } +#endif printk(KERN_INFO "ATI board detected. Using APIC/PM timer.\n"); apic_runs_main_timer = 1; -- 2.41.1