Re: [PATCH v3] xhci-pci: Set runtime PM as default policy on all xHC 1.2 or later devices

[Mika Westerberg]

On Mon, Oct 10, 2022 at 11:00:21AM -0500, Mario Limonciello wrote:
> For optimal power consumption of USB4 routers the XHCI PCIe endpoint
> used for tunneling must be in D3.  Historically this is accomplished
> by a long list of PCIe IDs that correspond to these endpoints because
> the xhci_hcd driver will not default to allowing runtime PM for all
> devices.
> 
> As both AMD and Intel have released new products with new XHCI controllers
> this list continues to grow. In reviewing the XHCI specification v1.2 on
> page 607 there is already a requirement that the PCI power management
> states D3hot and D3cold must be supported.
> 
> In the quirk list, use this to indicate that runtime PM should be allowed
> on XHCI controllers. The following controllers are known to be xHC 1.2 and
> dropped explicitly:
> * AMD Yellow Carp
> * Intel Alder Lake
> * Intel Meteor Lake
> * Intel Raptor Lake
> 
> Suggested-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
> Link: https://www.intel.com/content/dam/www/public/us/en/documents/technical-specifications/extensible-host-controler-interface-usb-xhci.pdf
> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>

Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>