diff options
| author | john stultz <johnstul@us.ibm.com> | 2006-12-08 02:36:02 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-12-08 08:28:37 -0800 |
| commit | 562f9c574e0707f9159a729ea41faf53b221cd30 (patch) | |
| tree | 54fb7d5195d09cd7ce9ceb312a98d7538e8a34f0 /drivers/clocksource | |
| parent | a2ee8649ba6d71416712e798276bf7c40b64e6e5 (diff) | |
[PATCH] time: re-add verify_pmtmr_rate
This patch re-adds the verify_pmtmr_rate functionality from 2.6.17 that
I dropped 2.6.18.
This resolves problems seen on older K6 ASUS boards where the ACPI PM
timer runs too fast.
See:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=211902
http://bugme.osdl.org/show_bug.cgi?id=2375
Thanks to Ian Campbell for re-reporting this and testing the fix!
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Ian Campbell <ijc@hellion.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers/clocksource')
| -rw-r--r-- | drivers/clocksource/acpi_pm.c | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/drivers/clocksource/acpi_pm.c b/drivers/clocksource/acpi_pm.c index 7fcb77a9d011..8ab61ef97b4c 100644 --- a/drivers/clocksource/acpi_pm.c +++ b/drivers/clocksource/acpi_pm.c @@ -142,6 +142,39 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, PCI_DEVICE_ID_SERVERWORKS_LE, acpi_pm_check_graylist); #endif +#ifndef CONFIG_X86_64 +#include "mach_timer.h" +#define PMTMR_EXPECTED_RATE \ + ((CALIBRATE_LATCH * (PMTMR_TICKS_PER_SEC >> 10)) / (CLOCK_TICK_RATE>>10)) +/* + * Some boards have the PMTMR running way too fast. We check + * the PMTMR rate against PIT channel 2 to catch these cases. + */ +static int verify_pmtmr_rate(void) +{ + u32 value1, value2; + unsigned long count, delta; + + mach_prepare_counter(); + value1 = read_pmtmr(); + mach_countup(&count); + value2 = read_pmtmr(); + delta = (value2 - value1) & ACPI_PM_MASK; + + /* Check that the PMTMR delta is within 5% of what we expect */ + if (delta < (PMTMR_EXPECTED_RATE * 19) / 20 || + delta > (PMTMR_EXPECTED_RATE * 21) / 20) { + printk(KERN_INFO "PM-Timer running at invalid rate: %lu%% " + "of normal - aborting.\n", + 100UL * delta / PMTMR_EXPECTED_RATE); + return -1; + } + + return 0; +} +#else +#define verify_pmtmr_rate() (0) +#endif static int __init init_acpi_pm_clocksource(void) { @@ -173,6 +206,9 @@ static int __init init_acpi_pm_clocksource(void) return -ENODEV; pm_good: + if (verify_pmtmr_rate() != 0) + return -ENODEV; + return clocksource_register(&clocksource_acpi_pm); } |