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

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Date:   Wed, 16 Oct 2019 18:38:16 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de
Cc:     hpa@...or.com, harry.pan@...el.com, feng.tang@...el.com,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        stable@...r.kernel.org
Subject: [PATCH] x86/intel: Disable HPET on Intel Coffe Lake platforms

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@...r.kernel.org>
Suggested-by: Feng Tang <feng.tang@...el.com>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.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