storage: accept some UAS devices if streams are unavailable

On some older XHCIs streams are not supported and the UAS driver
will fail at probe time. For those devices storage should try
to bind to UAS devices.
This patch adds a flag for stream support to HCDs and evaluates
it.

[Note: Sarah fixed a bug where the USB 2.0 root hub, not USB 3.0 root
hub would get marked as being able to support streams.]
Signed-off-by: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>

drivers/usb/host/xhci-pci.c

@@ -222,6 +222,9 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
 		goto put_usb3_hcd;
 	/* Roothub already marked as USB 3.0 speed */
 
+	if (HCC_MAX_PSA(xhci->hcc_params) >= 4)
+		xhci->shared_hcd->can_do_streams = 1;
+
 	return 0;
 
 put_usb3_hcd:

drivers/usb/host/xhci-plat.c

@@ -158,6 +158,9 @@ static int xhci_plat_probe(struct platform_device *pdev)
 	 */
 	*((struct xhci_hcd **) xhci->shared_hcd->hcd_priv) = xhci;
 
+	if (HCC_MAX_PSA(xhci->hcc_params) >= 4)
+		xhci->shared_hcd->can_do_streams = 1;
+
 	ret = usb_add_hcd(xhci->shared_hcd, irq, IRQF_SHARED);
 	if (ret)
 		goto put_usb3_hcd;

drivers/usb/storage/uas-detect.h

@@ -72,6 +72,7 @@ static int uas_use_uas_driver(struct usb_interface *intf,
 {
 	struct usb_host_endpoint *eps[4] = { };
 	struct usb_device *udev = interface_to_usbdev(intf);
+	struct usb_hcd *hcd = bus_to_hcd(udev->bus);
 	unsigned long flags = id->driver_info;
 	int r, alt;
 
@@ -80,6 +81,9 @@ static int uas_use_uas_driver(struct usb_interface *intf,
 	if (flags & US_FL_IGNORE_UAS)
 		return 0;
 
+	if (udev->speed >= USB_SPEED_SUPER && !hcd->can_do_streams)
+		return 0;
+
 	alt = uas_find_uas_alt_setting(intf);
 	if (alt < 0)
 		return 0;

include/linux/usb/hcd.h

@@ -143,6 +143,7 @@ struct usb_hcd {
 	unsigned		authorized_default:1;
 	unsigned		has_tt:1;	/* Integrated TT in root hub */
 	unsigned		amd_resume_bug:1; /* AMD remote wakeup quirk */
+	unsigned		can_do_streams:1; /* HC supports streams */
 
 	unsigned int		irq;		/* irq allocated */
 	void __iomem		*regs;		/* device memory/io */