Patch "x86/quirks: Disable HPET on Intel Coffe Lake platforms" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

x86/quirks: Disable HPET on Intel Coffe Lake platforms

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-quirks-disable-hpet-on-intel-coffe-lake-platforms.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From fc5db58539b49351e76f19817ed1102bf7c712d0 Mon Sep 17 00:00:00 2001
From: Kai-Heng Feng <[email protected]>
Date: Wed, 16 Oct 2019 18:38:16 +0800
Subject: x86/quirks: Disable HPET on Intel Coffe Lake platforms

From: Kai-Heng Feng <[email protected]>

commit fc5db58539b49351e76f19817ed1102bf7c712d0 upstream.

Some Coffee Lake platforms have a skewed HPET timer once the SoCs entered PC10, which in consequence marks TSC as unstable because HPET is used as watchdog clocksource for TSC.

Harry Pan tried to work around it in the clocksource watchdog code [1] thereby creating a circular dependency between HPET and TSC. This also ignores the fact, that HPET is not only unsuitable as watchdog clocksource on these systems, it becomes unusable in general.

Disable HPET on affected platforms.

Suggested-by Feng Tang <[email protected]>

Signed-off-by Kai-Heng Feng <[email protected]>

Signed-off-by Thomas Gleixner <[email protected]>

Cc [email protected]

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203183

Link https://lore.kernel.org/lkml/[email protected]/ [1] open here

Link https://lkml.kernel.org/r/[email protected] open here

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
arch/x86/kernel/early-quirks.c | 2 ++

1 file changed, 2 insertions(+)

arch/x86/kernel/early-quirks.c +2 -0

@@ -699,6 +699,8 @@ static struct chipset early_qrk[] __init
 	 */
 	{ PCI_VENDOR_ID_INTEL, 0x0f00,
 		PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, force_disable_hpet},
+	{ PCI_VENDOR_ID_INTEL, 0x3ec4,
+		PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, force_disable_hpet},
 	{ PCI_VENDOR_ID_BROADCOM, 0x4331,
 	  PCI_CLASS_NETWORK_OTHER, PCI_ANY_ID, 0, apple_airport_reset},
 	{}

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/x86-quirks-disable-hpet-on-intel-coffe-lake-platforms.patch

Hi Greg,

Quoted 14 lines · On Nov 18, 2019, at 23:55, <[email protected]>…

This is a note to let you know that I've just added the patch titled

x86/quirks: Disable HPET on Intel Coffe Lake platforms

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-quirks-disable-hpet-on-intel-coffe-lake-platforms.patch
and it can be found in the queue-4.4 subdirectory.

Quoted 2 lines

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

This patch depends on commit c8c4076723da ("x86/timer: Skip PIT initialization on modern chipsets"). Otherwise the system may freeze at boot. So please also include that commit.

Quoted 16 lines · Kai-Heng Feng

Hi Greg,

Quoted 14 lines · On Nov 18, 2019, at 23:55, <[email protected]>…

This is a note to let you know that I've just added the patch titled

x86/quirks: Disable HPET on Intel Coffe Lake platforms

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-quirks-disable-hpet-on-intel-coffe-lake-platforms.patch
and it can be found in the queue-4.4 subdirectory.

Quoted 5 lines

Quoted 2 lines

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

This patch depends on commit c8c4076723da ("x86/timer: Skip PIT initialization on modern chipsets"). Otherwise the system may freeze at boot. So please also include that commit.

Thanks for the info, now queued up everywhere.