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@xxxxxxxxxxxxxxx
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
---
drivers/usb/host/xhci-pci.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index b5016709b26f..fb988e4ea924 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -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);
}
--
2.25.1
