linux/arch/x86
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
..
boot Merge branch 'x86-setup-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-02-28 10:43:53 -08:00
configs
crypto tree-wide: Assorted spelling fixes 2010-02-09 11:13:56 +01:00
ia32 Add generic sys_olduname() 2010-03-12 15:52:32 -08:00
include/asm x86, amd: Restrict usage of c1e_idle() 2010-03-19 14:43:36 -07:00
kernel x86, hpet: Erratum workaround for read after write of HPET comparator 2010-04-01 15:21:47 -07:00
kvm Merge branch 'kvm-updates/2.6.34' of git://git.kernel.org/pub/scm/virt/kvm/kvm 2010-03-05 13:12:34 -08:00
lguest
lib Merge branch 'x86-rwsem-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-02-28 10:41:35 -08:00
math-emu
mm x86: Make sure free_init_pages() frees pages on page boundary 2010-03-29 18:55:33 +02:00
oprofile perf, x86: rename macro in ARCH_PERFMON_EVENTSEL_ENABLE 2010-03-01 14:21:23 +01:00
pci x86/PCI: truncate _CRS windows with _LEN > _MAX - _MIN + 1 2010-03-25 10:14:13 -07:00
power x86-32, resume: do a global tlb flush in S4 resume 2010-03-30 11:46:02 -07:00
tools x86: Remove trailing spaces in messages 2010-02-07 17:47:51 +01:00
vdso sysctl x86: Remove dead binary sysctl support 2009-11-12 02:05:04 -08:00
video
xen Merge branch 'for-next' into for-linus 2010-03-08 16:55:37 +01:00
Kbuild
Kconfig Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-03-13 14:45:49 -08:00
Kconfig.cpu Merge branch 'x86-rwsem-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-02-28 10:41:35 -08:00
Kconfig.debug Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-12-11 20:47:30 -08:00
Makefile x86-64: Allow fbdev primary video code 2010-02-16 21:22:26 -08:00
Makefile_32.cpu Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-12-08 13:38:11 -08:00