Re: [PATCH] PCI/PM: Don't call pci_pm_power_up_and_verify_state() for devices already in D0

[Lukas Wunner <lukas@wunner.de>]

On Wed, Mar 04, 2026 at 05:03:24PM +0000, Rich Hanes wrote:
> Reproduced on a Lenovo ThinkPad with Intel Wireless-AC 7265 (8086:095a)
> behind PCIe root port 8086:9d10.  The workaround pcie_aspm=off confirms
> that suppressing L1 PM substate configuration prevents the failure.

The same issue was observed on a Google Pixelbook Eve:
https://bugzilla.kernel.org/show_bug.cgi?id=220705

That laptop also uses an i7265 attached to a Sunrise Point-LP PCH.

The PCH suffers from a hardware erratum, it doesn't reinstate the
clock quick enough after CLREQ# assertion to stay below the
spec-prescribed 400 nsec.

Intel's specification update recommends disabling CLKREQ# support
at the Root Port to work around the issue.  This must be done by
the BIOS, an operating system patch isn't the right approach.

I've prepared a BIOS change for the coreboot BIOS used on the
Pixelbook, see the above-linked bugzilla.  It has not been
upstreamed yet as I'm waiting on the reporter to test it.

If your ThinkPad can be made to boot with coreboot, I can look into
porting the patch over to your machine.  Please specify the exact
Thinkpad model you're using.  Otherwise please check whether Lenovo
has released a BIOS update for your machine.

Thanks,

Lukas