Hi Julian,
於 二，2014-03-11 於 18:15 +0100，Julian Wollrath 提到：
> Am Tue, 11 Mar 2014 14:56:41 +0100 (CET)
> schrieb Thomas Gleixner <t...@linutronix.de>:
> > > Ok, via bisecting I found commit
> > > 73f7d1ca32638028e3271f54616773727e2f9f26 (see below) to be the one
> > > that introduced this regression.
> >
> > Interesting. I have no idea what's going on. But maybe can the ACPI
> > folks shed some light on it.
>
My patch moved acpi_early_init() to before timekeeping_init() is for
prepare the later using ACPI TAD to set system clock. I think that
because acpi_early_init() setup SCI interrupt and enable acpi subsystem,
it causes fast TSC calibration fail.
> I have absolutely no idea, if it is the right thing to do and why it
> works, but the patch below fixes the problem. Thank you for your help.
>
>
> Cheers,
> Julian Wollrath
>
> From 7664f495039d93adfce073e58840a46549904f04 Mon Sep 17 00:00:00 2001
> From: Julian Wollrath <jwollr...@web.de>
> Date: Tue, 11 Mar 2014 18:05:43 +0100
> Subject: [PATCH] Fix fast TSC calibration
>
> Since commit 73f7d1ca32638028e3271f54616773727e2f9f26 the fast TSC calibration
> failed on a Thinkpad X121e with an AMD E450 APU. Moving acpi_early_init()
> after
> late_time_init() fixes this.
>
> Signed-off-by: Julian Wollrath <jwollr...@web.de>
> ---
> init/main.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/init/main.c b/init/main.c
> index eb03090cdced..bf9d99148bd6 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -561,7 +561,6 @@ asmlinkage void __init start_kernel(void)
> init_timers();
> hrtimers_init();
> softirq_init();
> - acpi_early_init();
> timekeeping_init();
> time_init();
> sched_clock_postinit();
> @@ -609,6 +608,7 @@ asmlinkage void __init start_kernel(void)
> numa_policy_init();
> if (late_time_init)
> late_time_init();
> + acpi_early_init();
> sched_clock_init();
> calibrate_delay();
> pidmap_init();
The late_time_init() dependent on timekeeping_init(), if we don't want
move acpi_early_init() before timekeeping_init() then just direct put it
before efi_enter_virtual_mode() because we tested this changed.
This patch restricts the position to run acpi_early_init() before
timekeeping_init() when only "CMOS RTC Not Present" bit set in FADT.
Could you please help to test it on your machine?
Thanks a lot!
Joey Lee
>From 8ef4fff76dd2f50bef1e8eb9c96f3b0228a38401 Mon Sep 17 00:00:00 2001
From: Lee, Chun-Yi <j...@suse.com>
Date: Wed, 12 Mar 2014 11:36:32 +0800
Subject: [PATCH] ACPI / init: Run acpi_early_init() before timekeeping_init()
when CMOS RTC Not Present bit set
This is a variant patch from Rafael J. Wysocki's
ACPI / init: Run acpi_early_init() before efi_enter_virtual_mode()
According to Matt Fleming, if acpi_early_init() was executed before
efi_enter_virtual_mode(), the EFI initialization could benefit from
it, so Rafael's patch makes that happen.
And, later we want accessing ACPI TAD device to set system clock, so
move acpi_early_init() before timekeeping_init() when "CMOS RTC Not
Present" bit set. This position is also before efi_enter_virtual_mode().
Signed-off-by: Lee, Chun-Yi <j...@suse.com>
---
init/main.c | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/init/main.c b/init/main.c
index eb03090..e1b69d2 100644
--- a/init/main.c
+++ b/init/main.c
@@ -561,7 +561,9 @@ asmlinkage void __init start_kernel(void)
init_timers();
hrtimers_init();
softirq_init();
- acpi_early_init();
+ if (acpi_gbl_FADT.header.revision >= 5 &&
+ acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_CMOS_RTC)
+ acpi_early_init();
timekeeping_init();
time_init();
sched_clock_postinit();
@@ -613,6 +615,9 @@ asmlinkage void __init start_kernel(void)
calibrate_delay();
pidmap_init();
anon_vma_init();
+ if (!(acpi_gbl_FADT.header.revision >= 5 &&
+ acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_CMOS_RTC))
+ acpi_early_init();
#ifdef CONFIG_X86
if (efi_enabled(EFI_RUNTIME_SERVICES))
efi_enter_virtual_mode();
--
1.6.4.2
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