[PATCH] x86/intel: Disable HPET on Intel Coffe Lake platforms

[PATCH] x86/intel: Disable HPET on Intel Coffe Lake platforms

[Kai-Heng Feng]

Some Coffee Lake platforms have skewed HPET timer once the SoCs entered
PC10, and marked TSC as unstable clocksource as result.

Harry Pan identified it's a firmware bug [1].

To prevent creating a circular dependency between HPET and TSC, let's
disable HPET on affected platforms.

[1]: https://lore.kernel.org/lkml/20190516090651.1396-1-harry.pan@intel.com/
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203183

Cc: <stable@vger.kernel.org>
Suggested-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
 arch/x86/kernel/early-quirks.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
index 6f6b1d04dadf..4cba91ec8049 100644
--- a/arch/x86/kernel/early-quirks.c
+++ b/arch/x86/kernel/early-quirks.c
@@ -710,6 +710,8 @@ static struct chipset early_qrk[] __initdata = {
 	 */
 	{ 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},
 	{}
-- 
2.17.1

Re: [PATCH] x86/intel: Disable HPET on Intel Coffe Lake platforms

[Kai-Heng Feng]

Hi Thomas,

> On Oct 16, 2019, at 18:38, Kai-Heng Feng <kai.heng.feng@canonical.com> wrote:
> 
> Some Coffee Lake platforms have skewed HPET timer once the SoCs entered
> PC10, and marked TSC as unstable clocksource as result.
> 
> Harry Pan identified it's a firmware bug [1].
> 
> To prevent creating a circular dependency between HPET and TSC, let's
> disable HPET on affected platforms.
> 
> [1]: https://lore.kernel.org/lkml/20190516090651.1396-1-harry.pan@intel.com/
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203183

Do you think it's a sane approach?

Kai-Heng

> 
> Cc: <stable@vger.kernel.org>
> Suggested-by: Feng Tang <feng.tang@intel.com>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
> arch/x86/kernel/early-quirks.c | 2 ++
> 1 file changed, 2 insertions(+)
> 
> diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
> index 6f6b1d04dadf..4cba91ec8049 100644
> --- a/arch/x86/kernel/early-quirks.c
> +++ b/arch/x86/kernel/early-quirks.c
> @@ -710,6 +710,8 @@ static struct chipset early_qrk[] __initdata = {
> 	 */
> 	{ 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},
> 	{}
> -- 
> 2.17.1
> 

[tip: x86/urgent] x86/quirks: Disable HPET on Intel Coffe Lake platforms

[tip-bot2 for Kai-Heng Feng]

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     fc5db58539b49351e76f19817ed1102bf7c712d0
Gitweb:        https://git.kernel.org/tip/fc5db58539b49351e76f19817ed1102bf7c712d0
Author:        Kai-Heng Feng <kai.heng.feng@canonical.com>
AuthorDate:    Wed, 16 Oct 2019 18:38:16 +08:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Tue, 12 Nov 2019 15:55:20 +01:00

x86/quirks: Disable HPET on Intel Coffe Lake platforms

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 <feng.tang@intel.com>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203183
Link: https://lore.kernel.org/lkml/20190516090651.1396-1-harry.pan@intel.com/ [1]
Link: https://lkml.kernel.org/r/20191016103816.30650-1-kai.heng.feng@canonical.com
---
 arch/x86/kernel/early-quirks.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
index 6f6b1d0..4cba91e 100644
--- a/arch/x86/kernel/early-quirks.c
+++ b/arch/x86/kernel/early-quirks.c
@@ -710,6 +710,8 @@ static struct chipset early_qrk[] __initdata = {
 	 */
 	{ 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},
 	{}