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authorAndi Kleen <ak@suse.de>2006-02-26 04:18:52 +0100
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-26 09:53:31 -0800
commitab9b32ee626e9b6df4ce2560a70ae15e62423cf4 (patch)
tree4bae7b0a38b9e69d33dc7b80ad434274019d9e38
parente8b917775b572bc27de105f1317c2de4335db5b3 (diff)
downloadlinux-linaro-ab9b32ee626e9b6df4ce2560a70ae15e62423cf4.tar.gz
[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 <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--Documentation/x86_64/boot-options.txt4
-rw-r--r--arch/x86_64/kernel/io_apic.c46
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 <asm/pci-direct.h>
#include <linux/pci_ids.h>
#include <linux/pci.h>
@@ -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);