From ab9b32ee626e9b6df4ce2560a70ae15e62423cf4 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Sun, 26 Feb 2006 04:18:52 +0100 Subject: [PATCH] x86_64: Better ATI timer fix The previous experiment for using apicmaintimer on ATI systems didn't work out very well. In particular laptops with C2/C3 support often don't let it tick during idle, which makes it useless. There were also some other bugs that made the apicmaintimer often not used at all. I tried some other experiments - running timer over RTC and some other things but they didn't really work well neither. I rechecked the specs now and it turns out this simple change is actually enough to avoid the double ticks on the ATI systems. We just turn off IRQ 0 in the 8254 and only route it directly using the IO-APIC. I tested it on a few ATI systems and it worked there. In fact it worked on all chipsets (NVidia, Intel, AMD, ATI) I tried it on. According to the ACPI spec routing should always work through the IO-APIC so I think it's the correct thing to do anyways (and most of the old gunk in check_timer should be thrown away for x86-64). But for 2.6.16 it's best to do a fairly minimal change: - Use the known to be working everywhere-but-ATI IRQ0 both over 8254 and IO-APIC setup everywhere - Except on ATI disable IRQ0 in the 8254 - Remove the code to select apicmaintimer on ATI chipsets - Add some boot options to allow to override this (just paranoia) In 2.6.17 I hope to switch the default over to this for everybody. Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- Documentation/x86_64/boot-options.txt | 4 +++ arch/x86_64/kernel/io_apic.c | 46 ++++++++++++++++++++++------------- 2 files changed, 33 insertions(+), 17 deletions(-) diff --git a/Documentation/x86_64/boot-options.txt b/Documentation/x86_64/boot-options.txt index 153740f460a..1921353259a 100644 --- a/Documentation/x86_64/boot-options.txt +++ b/Documentation/x86_64/boot-options.txt @@ -52,6 +52,10 @@ APICs apicmaintimer. Useful when your PIT timer is totally broken. + disable_8254_timer / enable_8254_timer + Enable interrupt 0 timer routing over the 8254 in addition to over + the IO-APIC. The kernel tries to set a sensible default. + Early Console syntax: earlyprintk=vga diff --git a/arch/x86_64/kernel/io_apic.c b/arch/x86_64/kernel/io_apic.c index ffab8a75666..ffed464e6b1 100644 --- a/arch/x86_64/kernel/io_apic.c +++ b/arch/x86_64/kernel/io_apic.c @@ -50,6 +50,8 @@ static int no_timer_check; int disable_timer_pin_1 __initdata; +int timer_over_8254 __initdata = 1; + /* Where if anywhere is the i8259 connect in external int mode */ static struct { int pin, apic; } ioapic_i8259 = { -1, -1 }; @@ -251,6 +253,20 @@ static int __init enable_ioapic_setup(char *str) __setup("noapic", disable_ioapic_setup); __setup("apic", enable_ioapic_setup); +static int __init setup_disable_8254_timer(char *s) +{ + timer_over_8254 = -1; + return 1; +} +static int __init setup_enable_8254_timer(char *s) +{ + timer_over_8254 = 2; + return 1; +} + +__setup("disable_8254_timer", setup_disable_8254_timer); +__setup("enable_8254_timer", setup_enable_8254_timer); + #include #include #include @@ -309,27 +325,20 @@ void __init check_ioapic(void) #endif /* RED-PEN skip them on mptables too? */ return; + + /* This should be actually default, but + for 2.6.16 let's do it for ATI only where + it's really needed. */ 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 + if (timer_over_8254 == 1) { + timer_over_8254 = 0; printk(KERN_INFO - "ATI board detected. Using APIC/PM timer.\n"); - apic_runs_main_timer = 1; - nohpet = 1; + "ATI board detected. Disabling timer routing over 8254.\n"); + } return; } + /* No multi-function device? */ type = read_pci_config_byte(num,slot,func, PCI_HEADER_TYPE); @@ -1773,6 +1782,8 @@ static inline void unlock_ExtINT_logic(void) * a wide range of boards and BIOS bugs. Fortunately only the timer IRQ * is so screwy. Thanks to Brian Perkins for testing/hacking this beast * fanatically on his truly buggy board. + * + * FIXME: really need to revamp this for modern platforms only. */ static inline void check_timer(void) { @@ -1795,7 +1806,8 @@ static inline void check_timer(void) */ apic_write(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_EXTINT); init_8259A(1); - enable_8259A_irq(0); + if (timer_over_8254 > 0) + enable_8259A_irq(0); pin1 = find_isa_irq_pin(0, mp_INT); apic1 = find_isa_irq_apic(0, mp_INT); -- cgit