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Pallipadi, Venkatesh 8da854cb02 x86, hpet: Erratum workaround for read after write of HPET comparator 
On Wed, Feb 24, 2010 at 03:37:04PM -0800, Justin Piszcz wrote:
> Hello,
>
> Again, on the Intel DP55KG board:
>
> # uname -a
> Linux host 2.6.33 #1 SMP Wed Feb 24 18:31:00 EST 2010 x86_64 GNU/Linux
>
> [    1.237600] ------------[ cut here ]------------
> [    1.237890] WARNING: at arch/x86/kernel/hpet.c:404 hpet_next_event+0x70/0x80()
> [    1.238221] Hardware name:
> [    1.238504] hpet: compare register read back failed.
> [    1.238793] Modules linked in:
> [    1.239315] Pid: 0, comm: swapper Not tainted 2.6.33 #1
> [    1.239605] Call Trace:
> [    1.239886]  <IRQ>  [<ffffffff81056c13>] ? warn_slowpath_common+0x73/0xb0
> [    1.240409]  [<ffffffff81079608>] ? tick_dev_program_event+0x38/0xc0
> [    1.240699]  [<ffffffff81056cb0>] ? warn_slowpath_fmt+0x40/0x50
> [    1.240992]  [<ffffffff81079608>] ? tick_dev_program_event+0x38/0xc0
> [    1.241281]  [<ffffffff81041ad0>] ? hpet_next_event+0x70/0x80
> [    1.241573]  [<ffffffff81079608>] ? tick_dev_program_event+0x38/0xc0
> [    1.241859]  [<ffffffff81078e32>] ? tick_handle_oneshot_broadcast+0xe2/0x100
> [    1.246533]  [<ffffffff8102a67a>] ? timer_interrupt+0x1a/0x30
> [    1.246826]  [<ffffffff81085499>] ? handle_IRQ_event+0x39/0xd0
> [    1.247118]  [<ffffffff81087368>] ? handle_edge_irq+0xb8/0x160
> [    1.247407]  [<ffffffff81029f55>] ? handle_irq+0x15/0x20
> [    1.247689]  [<ffffffff810294a2>] ? do_IRQ+0x62/0xe0
> [    1.247976]  [<ffffffff8146be53>] ? ret_from_intr+0x0/0xa
> [    1.248262]  <EOI>  [<ffffffff8102f277>] ? mwait_idle+0x57/0x80
> [    1.248796]  [<ffffffff8102645c>] ? cpu_idle+0x5c/0xb0
> [    1.249080] ---[ end trace db7f668fb6fef4e1 ]---
>
> Is this something Intel has to fix or is it a bug in the kernel?

This is a chipset erratum.

Thomas: You mentioned we can retain this check only for known-buggy and
hpet debug kind of options. But here is the simple workaround patch for
this particular erratum.

Some chipsets have a erratum due to which read immediately following a
write of HPET comparator returns old comparator value instead of most
recently written value.

Erratum 15 in
"Intel I/O Controller Hub 9 (ICH9) Family Specification Update"
(http://www.intel.com/assets/pdf/specupdate/316973.pdf)

Workaround for the errata is to read the comparator twice if the first
one fails.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
LKML-Reference: <20100225185348.GA9674@linux-os.sc.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@gmail.com>
Cc: <stable@kernel.org>
2010-04-01 15:21:47 -07:00
..
acpi Merge branches 'battery-2.6.34', 'bugzilla-10805', 'bugzilla-14668', 'bugzilla-531916-power-state', 'ht-warn-2.6.34', 'pnp', 'processor-rename', 'sony-2.6.34', 'suse-bugzilla-531547', 'tz-check', 'video' and 'misc-2.6.34' into release 2010-03-14 21:30:17 -04:00
apic x86: Handle legacy PIC interrupts on all the cpu's 2010-03-16 06:36:35 +01:00
cpu x86 / perf: Fix suspend to RAM on HP nx6325 2010-03-22 09:57:19 -07:00
.gitignore
alternative.c Merge branch 'perf-probes-for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-03-05 10:50:22 -08:00
amd_iommu_init.c x86/amd-iommu: Fix IOMMU-API initialization for iommu=pt 2010-01-22 17:44:35 +01:00
amd_iommu.c x86/amd-iommu: Fix deassignment of a device from the pt_domain 2010-01-22 17:56:49 +01:00
apb_timer.c Merge branch 'x86-mrst-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-03-07 15:59:39 -08:00
aperture_64.c x86/gart: Unexport gart_iommu_aperture 2010-02-16 22:05:09 +01:00
apm_32.c x86: Remove trailing spaces in messages 2010-02-07 17:47:51 +01:00
asm-offsets_32.c lguest: optimize by coding restore_flags and irq_enable in assembler. 2009-06-12 22:27:03 +09:30
asm-offsets_64.c tracing: Define NR_syscalls for x86_64 2009-08-26 21:29:58 +02:00
asm-offsets.c
audit_64.c
bios_uv.c Merge branch 'x86-uv-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-02-28 11:00:55 -08:00
bootflag.c
check.c
cpuid.c x86, msr/cpuid: Pass the number of minors when unregistering MSR and CPUID drivers. 2010-01-26 23:52:38 -08:00
crash_dump_32.c x86: crash_dump: Fix non-pae kdump kernel memory accesses 2009-10-26 12:38:59 +01:00
crash_dump_64.c
crash.c x86: Use x86_platform for iommu_shutdown 2009-11-08 13:12:26 +01:00
doublefault_32.c x86: Use get_desc_base() 2009-07-19 18:27:51 +02:00
ds_selftest.c
ds_selftest.h
ds.c percpu: make percpu symbols in x86 unique 2009-10-29 22:34:14 +09:00
dumpstack_32.c perf: Drop useless check for ignored frame 2010-01-13 10:09:08 +01:00
dumpstack_64.c perf/x86-64: Use frame pointer to walk on irq and process stacks 2010-03-10 14:26:40 +01:00
dumpstack.c perf: Stop stack frame walking off kernel addresses boundaries 2010-01-13 09:32:54 +01:00
dumpstack.h perf: Introduce new perf_fetch_caller_regs() for hot regs snapshot 2010-03-10 14:39:35 +01:00
e820.c x86: Make e820_remove_range to handle all covered case 2010-03-31 17:40:57 -07:00
early_printk.c x86: earlyprintk: Fix regression to handle serial,ttySn as 1 arg 2009-10-01 10:34:16 +02:00
early-quirks.c
efi_32.c
efi_64.c x86: Make 64-bit efi_ioremap use ioremap on MMIO regions 2009-08-03 13:34:25 -07:00
efi_stub_32.S
efi_stub_64.S
efi.c x86: Remove trailing spaces in messages 2010-02-07 17:47:51 +01:00
entry_32.S x86, 32-bit: Use same regs as 64-bit for kernel_thread_helper 2009-12-10 15:55:36 -08:00
entry_64.S Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-12-16 12:02:37 -08:00
ftrace.c Merge branch 'tracing/core' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing into tracing/core 2010-02-27 10:06:10 +01:00
head32.c x86: Make sure free_init_pages() frees pages on page boundary 2010-03-29 18:55:33 +02:00
head64.c x86: Make sure free_init_pages() frees pages on page boundary 2010-03-29 18:55:33 +02:00
head_32.S Merge branch 'master' into percpu 2010-01-05 09:17:33 +09:00
head_64.S tree-wide: Assorted spelling fixes 2010-02-09 11:13:56 +01:00
head.c
hpet.c x86, hpet: Erratum workaround for read after write of HPET comparator 2010-04-01 15:21:47 -07:00
hw_breakpoint.c Merge branch 'perf/core' into perf/urgent 2010-03-04 11:47:52 +01:00
i386_ksyms_32.c x86: Don't generate cmpxchg8b_emu if CONFIG_X86_CMPXCHG64=y 2009-10-01 08:42:24 +02:00
i387.c x86, ptrace: Remove set_stopped_child_used_math() in [x]fpregs_set 2010-02-23 13:45:27 -08:00
i8237.c
i8253.c x86: Do not unregister PIT clocksource on PIT oneshot setup/shutdown 2009-08-21 21:13:37 +02:00
i8259.c x86, pic: Fix section mismatch in legacy pic 2010-02-23 23:13:19 -08:00
init_task.c Use new __init_task_data macro in arch init_task.c files. 2009-09-21 06:27:08 +02:00
io_delay.c
ioport.c x86-64, paravirt: Call set_iopl_mask() on 64 bits 2009-12-09 16:54:08 -08:00
irq_32.c x86: Unify fixup_irqs() for 32-bit and 64-bit kernels 2009-11-02 15:56:34 +01:00
irq_64.c x86: Unify fixup_irqs() for 32-bit and 64-bit kernels 2009-11-02 15:56:34 +01:00
irq.c genirq: Convert irq_desc.lock to raw_spinlock 2009-12-14 23:55:33 +01:00
irqinit.c x86: Handle legacy PIC interrupts on all the cpu's 2010-03-16 06:36:35 +01:00
k8.c x86, k8 nb: Fix boot crash: enable k8_northbridges unconditionally on AMD systems 2010-03-13 08:36:16 +01:00
kdebugfs.c
kgdb.c perf, hw_breakpoint, kgdb: Do not take mutex for kernel debugger 2010-01-30 08:42:21 +01:00
kprobes.c kprobes/x86: Support kprobes jump optimization on x86 2010-02-25 17:49:26 +01:00
kvm.c KVM guest: do not batch pte updates from interrupt context 2009-09-10 18:10:50 +03:00
kvmclock.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-18 14:05:47 -07:00
ldt.c cpumask: use mm_cpumask() wrapper: x86 2009-09-24 09:34:52 +09:30
machine_kexec_32.c Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-12-08 13:27:33 -08:00
machine_kexec_64.c
Makefile x86, apbt: Moorestown APB system timer driver 2010-02-24 11:01:21 -08:00
mca_32.c
microcode_amd.c Revert "x86: ucode-amd: Load ucode-patches once ..." 2010-01-23 06:21:59 +01:00
microcode_core.c Revert "x86: ucode-amd: Load ucode-patches once ..." 2010-01-23 06:21:59 +01:00
microcode_intel.c x86: Remove trailing spaces in messages 2010-02-07 17:47:51 +01:00
mmconf-fam10h_64.c x86: Move range related operation to one file 2010-02-10 17:47:17 -08:00
module.c module: cleanup FIXME comments about trimming exception table entries. 2009-06-12 21:47:05 +09:30
mpparse.c x86: Handle overlapping mptables 2010-04-01 13:31:07 -07:00
mrst.c x86, mrst: Platform clock setup code 2010-02-24 11:01:33 -08:00
msr.c x86, msr/cpuid: Pass the number of minors when unregistering MSR and CPUID drivers. 2010-01-26 23:52:38 -08:00
olpc.c x86, olpc: Use pci subarch init for OLPC 2010-02-25 19:26:23 -08:00
paravirt_patch_32.c
paravirt_patch_64.c
paravirt-spinlocks.c locking: Convert __raw_spin* functions to arch_spin* 2009-12-14 23:55:32 +01:00
paravirt.c x86, paravirt: Remove kmap_atomic_pte paravirt op. 2010-02-27 14:41:35 -08:00
pci-calgary_64.c tree-wide: Assorted spelling fixes 2010-02-09 11:13:56 +01:00
pci-dma.c Merge branch 'for-next' into for-linus 2010-03-08 16:55:37 +01:00
pci-gart_64.c x86, k8 nb: Fix boot crash: enable k8_northbridges unconditionally on AMD systems 2010-03-13 08:36:16 +01:00
pci-nommu.c x86: Kill bad_dma_address variable 2009-11-17 07:53:21 +01:00
pci-swiotlb.c x86: Split swiotlb initialization into two stages 2009-12-15 13:01:57 +01:00
pcspeaker.c
pmtimer_64.c
probe_roms_32.c
process_32.c Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-02-28 10:35:09 -08:00
process_64.c Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-02-28 10:35:09 -08:00
process.c x86, amd: Restrict usage of c1e_idle() 2010-03-19 14:43:36 -07:00
ptrace.c Merge branch 'for-next' into for-linus 2010-03-08 16:55:37 +01:00
pvclock.c x86: Fix warning in pvclock.c 2009-07-14 16:25:05 +02:00
quirks.c x86: Disable HPET MSI on ATI SB700/SB800 2010-01-23 06:21:58 +01:00
reboot_fixups_32.c cs5535: move the DIVIL MSR definition into linux/cs5535.h 2009-12-15 08:53:28 -08:00
reboot.c x86: Add iMac9,1 to pci_reboot_dmi_table 2010-02-17 08:08:21 +01:00
relocate_kernel_32.S
relocate_kernel_64.S
rtc.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-18 14:05:47 -07:00
scx200_32.c
setup_percpu.c early_res: Add free_early_partial() 2010-02-26 08:25:35 +01:00
setup.c x86: Make sure free_init_pages() frees pages on page boundary 2010-03-29 18:55:33 +02:00
sfi.c SFI: remove unneeded includes 2009-09-15 15:08:40 -04:00
signal.c x86: Merge sys_sigaltstack 2009-12-09 16:28:59 -08:00
smp.c Revert "x86, timers: Check for pending timers after (device) interrupts" 2009-10-09 15:58:20 +02:00
smpboot.c x86: Handle legacy PIC interrupts on all the cpu's 2010-03-16 06:36:35 +01:00
stacktrace.c perf events, x86/stacktrace: Make stack walking optional 2009-12-17 09:56:19 +01:00
step.c x86: Use get_desc_base() 2009-07-19 18:27:51 +02:00
sys_i386_32.c Add generic sys_olduname() 2010-03-12 15:52:32 -08:00
sys_x86_64.c improve sys_newuname() for compat architectures 2010-03-12 15:52:32 -08:00
syscall_64.c
syscall_table_32.S Add generic sys_old_mmap() 2010-03-12 15:52:32 -08:00
tboot.c x86, intel_txt: clean up the impact on generic code, unbreak non-x86 2009-09-01 18:25:07 -07:00
tce_64.c
test_nx.c
test_rodata.c
time.c x86: Convert i8259_lock to raw_spinlock 2010-02-16 18:21:32 +01:00
tlb_uv.c Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-12-08 13:27:33 -08:00
tls.c
tls.h
topology.c
trampoline_32.S x86: cpuinit-annotate SMP boot trampolines properly 2009-09-20 20:23:37 +02:00
trampoline_64.S x86: Fix Suspend to RAM freeze on Acer Aspire 1511Lmi laptop 2009-10-12 18:06:48 +02:00
trampoline.c x86: Use find_e820() instead of hard coded trampoline address 2009-12-11 09:28:22 +01:00
traps.c x86/debug: Clear reserved bits of DR6 in do_debug() 2010-01-29 02:26:10 +01:00
tsc_sync.c locking: Convert __raw_spin* functions to arch_spin* 2009-12-14 23:55:32 +01:00
tsc.c Merge branch 'for-next' into for-linus 2010-03-08 16:55:37 +01:00
uv_irq.c x86, irq: Allow 0xff for /proc/irq/[n]/smp_affinity on an 8-cpu system 2009-12-17 22:03:06 -08:00
uv_sysfs.c x86: Remove trailing spaces in messages 2010-02-07 17:47:51 +01:00
uv_time.c x86, UV: Fix RTC latency bug by reading replicated cachelines 2010-01-27 11:33:53 +01:00
verify_cpu_64.S
visws_quirks.c Merge remote branch 'origin/x86/apic' into x86/mrst 2010-02-22 16:25:18 -08:00
vm86_32.c x86, 32-bit: Convert sys_vm86 & sys_vm86old 2009-12-09 16:29:23 -08:00
vmi_32.c x86, paravirt: Remove kmap_atomic_pte paravirt op. 2010-02-27 14:41:35 -08:00
vmiclock_32.c Merge branch 'for-next' into for-linus 2010-03-08 16:55:37 +01:00
vmlinux.lds.S x86: Make smp_locks end with page alignment 2010-03-29 18:42:30 +02:00
vsmp_64.c
vsyscall_64.c x86: Raise vsyscall priority on hotplug notifier chain 2010-03-01 12:35:40 -03:00
x86_init.c Merge branch 'x86-mrst-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-03-07 15:59:39 -08:00
x8664_ksyms_64.c x86-64: Modify copy_user_generic() alternatives mechanism 2009-12-30 11:57:31 +01:00
xsave.c x86, ptrace: regset extensions to support xstate 2010-02-11 15:08:17 -08:00