usb: xhci: change enumeration scheme to 'new scheme' by default

Change the default enumeration scheme for xhci attached non-SuperSpeed
devices from:

Reset
SetAddress [xhci address-device BSR = 0]
GetDescriptor(8)
GetDescriptor(18)

...to:

Reset
[xhci address-device BSR = 1]
GetDescriptor(64)
Reset
SetAddress [xhci address-device BSR = 0]
GetDescriptor(18)

...as some devices misbehave when encountering a SetAddress command
prior to GetDescriptor. There are known legacy devices that require
this scheme, but testing has found at least one USB3 device that fails
enumeration when presented with this ordering. For now, follow the ehci
case and enable 'new scheme' by default for non-SuperSpeed devices.

To support this enumeration scheme on xhci the AddressDevice operation
needs to be performed twice. The first instance of the command enables
the HC's device and slot context info for the device, but omits sending
the device a SetAddress command (BSR == block set address request).
Then, after GetDescriptor completes, follow up with the full
AddressDevice+SetAddress operation.

As mentioned before, this ordering of events with USB3 devices causes an
extra state transition to be exposed to xhci. Previously USB3 devices
would transition directly from 'enabled' to 'addressed' and never need
to underrun responses to 'get descriptor'. We do see the 64-byte
descriptor fetch the correct data, but the following 18-byte descriptor
read after the reset gets:

bLength = 0
bDescriptorType = 0
bcdUSB = 0
bDeviceClass = 0
bDeviceSubClass = 0
bDeviceProtocol = 0
bMaxPacketSize0 = 9

instead of:

bLength = 12
bDescriptorType = 1
bcdUSB = 300
bDeviceClass = 0
bDeviceSubClass = 0
bDeviceProtocol = 0
bMaxPacketSize0 = 9

which results in the discovery process looping until falling back to
'old scheme' enumeration.

Acked-by: Alan Stern <[e-mail]>
Reported-by: David Moore <[e-mail]>
Suggested-by: Sarah Sharp <[e-mail]>
Reported-by: Dan Carpenter <[e-mail]>
Signed-off-by: Dan Williams <[e-mail]>
Signed-off-by: Sarah Sharp <[e-mail]>

drivers/usb/core/hub.c

···
 #define HUB_LONG_RESET_TIME	200
 #define HUB_RESET_TIMEOUT	800
 
+/*
+ * "New scheme" enumeration causes an extra state transition to be
+ * exposed to an xhci host and causes USB3 devices to receive control
+ * commands in the default state.  This has been seen to cause
+ * enumeration failures, so disable this enumeration scheme for USB3
+ * devices.
+ */
+static bool use_new_scheme(struct usb_device *udev, int retry)
+{
+	if (udev->speed == USB_SPEED_SUPER)
+		return false;
+
+	return USE_NEW_SCHEME(retry);
+}
+
 static int hub_port_reset(struct usb_hub *hub, int port1,
 			struct usb_device *udev, unsigned int delay, bool warm);
 
···
 	}
 }
 
+static int hub_enable_device(struct usb_device *udev)
+{
+	struct usb_hcd *hcd = bus_to_hcd(udev->bus);
+
+	if (!hcd->driver->enable_device)
+		return 0;
+	if (udev->state == USB_STATE_ADDRESS)
+		return 0;
+	if (udev->state != USB_STATE_DEFAULT)
+		return -EINVAL;
+
+	return hcd->driver->enable_device(hcd, udev);
+}
+
 /* Reset device, (re)assign address, get device descriptor.
  * Device connection must be stable, no more debouncing needed.
  * Returns device in USB_STATE_ADDRESS, except on error.
···
 	 * this area, and this is how Linux has done it for ages.
 	 * Change it cautiously.
 	 *
-	 * NOTE:  If USE_NEW_SCHEME() is true we will start by issuing
+	 * NOTE:  If use_new_scheme() is true we will start by issuing
 	 * a 64-byte GET_DESCRIPTOR request.  This is what Windows does,
 	 * so it may help with some non-standards-compliant devices.
 	 * Otherwise we start with SET_ADDRESS and then try to read the
···
 	 * value.
 	 */
 	for (i = 0; i < GET_DESCRIPTOR_TRIES; (++i, msleep(100))) {
-		if (USE_NEW_SCHEME(retry_counter) && !(hcd->driver->flags & HCD_USB3)) {
+		bool did_new_scheme = false;
+
+		if (use_new_scheme(udev, retry_counter)) {
 			struct usb_device_descriptor *buf;
 			int r = 0;
+
+			did_new_scheme = true;
+			retval = hub_enable_device(udev);
+			if (retval < 0)
+				goto fail;
 
 #define GET_DESCRIPTOR_BUFSIZE	64
 			buf = kmalloc(GET_DESCRIPTOR_BUFSIZE, GFP_NOIO);
···
 			 *  - read ep0 maxpacket even for high and low speed,
 			 */
 			msleep(10);
-			if (USE_NEW_SCHEME(retry_counter) && !(hcd->driver->flags & HCD_USB3))
+			/* use_new_scheme() checks the speed which may have
+			 * changed since the initial look so we cache the result
+			 * in did_new_scheme
+			 */
+			if (did_new_scheme)
 				break;
 		}
 

drivers/usb/host/xhci-pci.c

···
 	.check_bandwidth =	xhci_check_bandwidth,
 	.reset_bandwidth =	xhci_reset_bandwidth,
 	.address_device =	xhci_address_device,
+	.enable_device =	xhci_enable_device,
 	.update_hub_device =	xhci_update_hub_device,
 	.reset_device =		xhci_discover_or_reset_device,
 

drivers/usb/host/xhci-plat.c

···
 	.check_bandwidth =	xhci_check_bandwidth,
 	.reset_bandwidth =	xhci_reset_bandwidth,
 	.address_device =	xhci_address_device,
+	.enable_device =	xhci_enable_device,
 	.update_hub_device =	xhci_update_hub_device,
 	.reset_device =		xhci_discover_or_reset_device,
 

drivers/usb/host/xhci-ring.c

···
 
 /* Queue an address device command TRB */
 int xhci_queue_address_device(struct xhci_hcd *xhci, dma_addr_t in_ctx_ptr,
-		u32 slot_id)
+			      u32 slot_id, enum xhci_setup_dev setup)
 {
 	return queue_command(xhci, lower_32_bits(in_ctx_ptr),
 			upper_32_bits(in_ctx_ptr), 0,
-			TRB_TYPE(TRB_ADDR_DEV) | SLOT_ID_FOR_TRB(slot_id),
-			false);
+			TRB_TYPE(TRB_ADDR_DEV) | SLOT_ID_FOR_TRB(slot_id)
+			| (setup == SETUP_CONTEXT_ONLY ? TRB_BSR : 0), false);
 }
 
 int xhci_queue_vendor_command(struct xhci_hcd *xhci,

drivers/usb/host/xhci.c

···
 }
 
 /*
- * Issue an Address Device command (which will issue a SetAddress request to
- * the device).
+ * Issue an Address Device command and optionally send a corresponding
+ * SetAddress request to the device.
  * We should be protected by the usb_address0_mutex in khubd's hub_port_init, so
  * we should only issue and wait on one address command at the same time.
  */
-int xhci_address_device(struct usb_hcd *hcd, struct usb_device *udev)
+static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev,
+			     enum xhci_setup_dev setup)
 {
 	unsigned long flags;
 	int timeleft;
···
 	spin_lock_irqsave(&xhci->lock, flags);
 	cmd_trb = xhci_find_next_enqueue(xhci->cmd_ring);
 	ret = xhci_queue_address_device(xhci, virt_dev->in_ctx->dma,
-					udev->slot_id);
+					udev->slot_id, setup);
 	if (ret) {
 		spin_unlock_irqrestore(&xhci->lock, flags);
 		xhci_dbg_trace(xhci, trace_xhci_dbg_address,
···
 		       le32_to_cpu(slot_ctx->dev_state) & DEV_ADDR_MASK);
 
 	return 0;
+}
+
+int xhci_address_device(struct usb_hcd *hcd, struct usb_device *udev)
+{
+	return xhci_setup_device(hcd, udev, SETUP_CONTEXT_ADDRESS);
+}
+
+int xhci_enable_device(struct usb_hcd *hcd, struct usb_device *udev)
+{
+	return xhci_setup_device(hcd, udev, SETUP_CONTEXT_ONLY);
 }
 
 /*

drivers/usb/host/xhci.h

···
 };
 
 /* flags bitmasks */
+
+/* Address device - disable SetAddress */
+#define TRB_BSR		(1<<9)
+enum xhci_setup_dev {
+	SETUP_CONTEXT_ONLY,
+	SETUP_CONTEXT_ADDRESS,
+};
+
 /* bits 16:23 are the virtual function ID */
 /* bits 24:31 are the slot ID */
 #define TRB_TO_SLOT_ID(p)	(((p) & (0xff<<24)) >> 24)
···
 		struct usb_host_endpoint **eps, unsigned int num_eps,
 		gfp_t mem_flags);
 int xhci_address_device(struct usb_hcd *hcd, struct usb_device *udev);
+int xhci_enable_device(struct usb_hcd *hcd, struct usb_device *udev);
 int xhci_update_device(struct usb_hcd *hcd, struct usb_device *udev);
 int xhci_set_usb2_hardware_lpm(struct usb_hcd *hcd,
 				struct usb_device *udev, int enable);
···
 void xhci_ring_cmd_db(struct xhci_hcd *xhci);
 int xhci_queue_slot_control(struct xhci_hcd *xhci, u32 trb_type, u32 slot_id);
 int xhci_queue_address_device(struct xhci_hcd *xhci, dma_addr_t in_ctx_ptr,
-		u32 slot_id);
+		u32 slot_id, enum xhci_setup_dev);
 int xhci_queue_vendor_command(struct xhci_hcd *xhci,
 		u32 field1, u32 field2, u32 field3, u32 field4);
 int xhci_queue_stop_endpoint(struct xhci_hcd *xhci, int slot_id,

include/linux/usb/hcd.h

···
 	void	(*reset_bandwidth)(struct usb_hcd *, struct usb_device *);
 		/* Returns the hardware-chosen device address */
 	int	(*address_device)(struct usb_hcd *, struct usb_device *udev);
+		/* prepares the hardware to send commands to the device */
+	int	(*enable_device)(struct usb_hcd *, struct usb_device *udev);
 		/* Notifies the HCD after a hub descriptor is fetched.
 		 * Will block.
 		 */