On 14.2.2024 15.00, Mathias Nyman wrote:
On 14.2.2024 14.58, Mathias Nyman wrote:
On 14.2.2024 11.31, Paul Menzel wrote:
Dear Linux folks,
As a follow-up to *Linux warning `usb: port power management may be unreliable` on Dell XPS 13 9360* [1][2], Linux warns about this on Dell laptops, desktops, and servers, and also on devices from other manufacturers [3].
Is this a firmware issue or a Linux one? As a user I am unsure what to do, and ignoring warnings sounds wrong to me.
At a fist glance it looks like a firmware issue.
USB2 and USB3 ports are in this case matched and peered based on the ports
ACPI _PLD (Physical Device Location) entries.
Usually there is only one USB2 and one USB3 port with exactly the same _PLD values,
but here it appears more ports return similar _PLD values.
Looks like these machines have _PLD ACPI objects for all USB ports, including
unusable USB host ports that are not wired to any connector or internal device.
All these unusable ports return similar _PLD objects, with zeroes in their group
token and position fields. This confuses the port peering code pairing USB2 and
USB3 ports that are wired to the same connector.
These unusable ports have a ACPI _UPC object stating they are not connectable.
We could probably tune the port peering code for those. At least skip
the warning messages.
Thanks
Mathias
