From 6bb74df481223731af6c7e0ff3adb31f6442cfcd Mon Sep 17 00:00:00 2001 From: john stultz Date: Mon, 5 Mar 2007 00:30:50 -0800 Subject: [PATCH] clocksource init adjustments (fix bug #7426) This patch resolves the issue found here: http://bugme.osdl.org/show_bug.cgi?id=7426 The basic summary is: Currently we register most of i386/x86_64 clocksources at module_init time. Then we enable clocksource selection at late_initcall time. This causes some problems for drivers that use gettimeofday for init calibration routines (specifically the es1968 driver in this case), where durring module_init, the only clocksource available is the low-res jiffies clocksource. This may cause slight calibration errors, due to the small sampling time used. It should be noted that drivers that require fine grained time may not function on architectures that do not have better then jiffies resolution timekeeping (there are a few). However, this does not discount the reasonable need for such fine-grained timekeeping at init time. Thus the solution here is to register clocksources earlier (ideally when the hardware is being initialized), and then we enable clocksource selection at fs_initcall (before device_initcall). This patch should probably get some testing time in -mm, since clocksource selection is one of the most important issues for correct timekeeping, and I've only been able to test this on a few of my own boxes. Signed-off-by: John Stultz Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "David S. Miller" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/clocksource/acpi_pm.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'drivers/clocksource/acpi_pm.c') diff --git a/drivers/clocksource/acpi_pm.c b/drivers/clocksource/acpi_pm.c index ccaa6a39cb4b..d42060ede930 100644 --- a/drivers/clocksource/acpi_pm.c +++ b/drivers/clocksource/acpi_pm.c @@ -214,4 +214,7 @@ pm_good: return clocksource_register(&clocksource_acpi_pm); } -module_init(init_acpi_pm_clocksource); +/* We use fs_initcall because we want the PCI fixups to have run + * but we still need to load before device_initcall + */ +fs_initcall(init_acpi_pm_clocksource); -- cgit v1.2.3 From 1ff100d76ff76477a2ead3aac94d04f2e891f44e Mon Sep 17 00:00:00 2001 From: john stultz Date: Mon, 26 Mar 2007 21:32:19 -0800 Subject: [PATCH] correct slow acpi_pm rating On Bob's machine clocksource is selecting PIT over the ACPI PM timer, because he has the PIIX4 bug. That bug drops the ACPI PM timers rating to the same as the PIT, so that's why you're getting the PIT. Realistically, the PIT is much slower then even the triple read ACPI PM, so the de-ranking code is probably dropping it too far. So don't drop ACPI PM quite so low if we see the PIIX4 bug. Signed-off-by: John Stultz Cc: Bob Tracy Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/clocksource/acpi_pm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/clocksource/acpi_pm.c') diff --git a/drivers/clocksource/acpi_pm.c b/drivers/clocksource/acpi_pm.c index d42060ede930..5ac309ee7f05 100644 --- a/drivers/clocksource/acpi_pm.c +++ b/drivers/clocksource/acpi_pm.c @@ -90,7 +90,7 @@ __setup("acpi_pm_good", acpi_pm_good_setup); static inline void acpi_pm_need_workaround(void) { clocksource_acpi_pm.read = acpi_pm_read_slow; - clocksource_acpi_pm.rating = 110; + clocksource_acpi_pm.rating = 120; } /* -- cgit v1.2.3 From 8ce8e2f99a973c39c4aeddbe0966038196a8e71a Mon Sep 17 00:00:00 2001 From: Daniel Walker Date: Wed, 25 Apr 2007 14:27:06 -0400 Subject: ACPI: correct pathname in comment Signed-off-by: Daniel Walker Signed-off-by: Andrew Morton Signed-off-by: Len Brown --- drivers/clocksource/acpi_pm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/clocksource/acpi_pm.c') diff --git a/drivers/clocksource/acpi_pm.c b/drivers/clocksource/acpi_pm.c index 5ac309ee7f05..5cfcff532545 100644 --- a/drivers/clocksource/acpi_pm.c +++ b/drivers/clocksource/acpi_pm.c @@ -26,7 +26,7 @@ /* * The I/O port the PMTMR resides at. * The location is detected during setup_arch(), - * in arch/i386/acpi/boot.c + * in arch/i386/kernel/acpi/boot.c */ u32 pmtmr_ioport __read_mostly; -- cgit v1.2.3