Commit 74622f0a authored by Mathias Nyman's avatar Mathias Nyman Committed by Greg Kroah-Hartman
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xhci: Detect lpm incapable xHC USB3 roothub ports from ACPI tables 



USB3 ports on xHC hosts may have retimers that cause too long
exit latency to work with native USB3 U1/U2 link power management states.

For now only use usb_acpi_port_lpm_incapable() to evaluate if port lpm
should be disabled while setting up the USB3 roothub.

Other ways to identify lpm incapable ports can be added here later if
ACPI _DSM does not exist.

Limit this to Intel hosts for now, this is to my knowledge only
an Intel issue.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20230116142216.1141605-8-mathias.nyman@linux.intel.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent cd702d18

drivers/usb/host/xhci-pci.c

+34 −0
Original line number Diff line number Diff line
@@ -355,8 +355,38 @@ static void xhci_pme_acpi_rtd3_enable(struct pci_dev *dev) 
				NULL);

	ACPI_FREE(obj);

}



static void xhci_find_lpm_incapable_ports(struct usb_hcd *hcd, struct usb_device *hdev)

{

	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);

	struct xhci_hub *rhub = &xhci->usb3_rhub;

	int ret;

	int i;



	/* This is not the usb3 roothub we are looking for */

	if (hcd != rhub->hcd)

		return;



	if (hdev->maxchild > rhub->num_ports) {

		dev_err(&hdev->dev, "USB3 roothub port number mismatch\n");

		return;

	}



	for (i = 0; i < hdev->maxchild; i++) {

		ret = usb_acpi_port_lpm_incapable(hdev, i);



		dev_dbg(&hdev->dev, "port-%d disable U1/U2 _DSM: %d\n", i + 1, ret);



		if (ret >= 0) {

			rhub->ports[i]->lpm_incapable = ret;

			continue;

		}

	}

}



#else

static void xhci_pme_acpi_rtd3_enable(struct pci_dev *dev) { }

static void xhci_find_lpm_incapable_ports(struct usb_hcd *hcd, struct usb_device *hdev) { }

#endif /* CONFIG_ACPI */



/* called during probe() after chip reset completes */
@@ -392,6 +422,10 @@ static int xhci_pci_setup(struct usb_hcd *hcd) 
static int xhci_pci_update_hub_device(struct usb_hcd *hcd, struct usb_device *hdev,

				      struct usb_tt *tt, gfp_t mem_flags)

{

	/* Check if acpi claims some USB3 roothub ports are lpm incapable */

	if (!hdev->parent)

		xhci_find_lpm_incapable_ports(hcd, hdev);



	return xhci_update_hub_device(hcd, hdev, tt, mem_flags);

}