Hi Jakub, > My Lenovo T490s with i7-8665U had been marking TSC as unstable > since v5.13, resulting in very sluggish desktop experience... > > Kernel logs show: > > clocksource: timekeeping watchdog on CPU3: hpet read-back delay of 316000ns, attempt 4, marking unstable > tsc: Marking TSC unstable due to clocksource watchdog > TSC found unstable after boot, most likely due to broken BIOS. Use 'tsc=unstable'. > sched_clock: Marking unstable (14539801827657, -530891666)<-(14539319241737, -48307500) > clocksource: Checking clocksource tsc synchronization from CPU 3 to CPUs 0-2,6-7. > clocksource: Switched to clocksource hpet > > I have a 8086:3e34 bridge, also known as "Host bridge: Intel > Corporation Coffee Lake HOST and DRAM Controller (rev 0c)". > Add it to the list. > > We should perhaps consider applying this quirk more widely. > The Intel documentation does not list my device [1], but > linuxhw [2] does, and it seems to list a few more bridges > we do not currently cover (3e31, 3ecc, 3e35, 3e0f). I wish someone from Intel would be a little more forthcoming and chimed in about the other devices. I guess, we will cross that bridge when we get to it, so to speak. > [1] https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/8th-gen-core-family-datasheet-vol-2.pdf > [2] https://github.com/linuxhw/DevicePopulation/blob/master/README.md > > Cc: stable@xxxxxxxxxxxxxxx # v5.13+ > Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> > --- > v2: - add the dmesg output > --- > 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 38837dad46e6..7d2de04f8750 100644 > --- a/arch/x86/kernel/early-quirks.c > +++ b/arch/x86/kernel/early-quirks.c > @@ -716,6 +716,8 @@ static struct chipset early_qrk[] __initdata = { > PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, force_disable_hpet}, > { PCI_VENDOR_ID_INTEL, 0x3e20, > PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, force_disable_hpet}, > + { PCI_VENDOR_ID_INTEL, 0x3e34, > + 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_INTEL, 0x8a12, Thank you! Acked-by: Krzysztof Wilczyński <kw@xxxxxxxxx> Krzysztof
