Merge tag 'usb-4.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb

Pull USB updates from Greg KH:
 "Here is the big USB drivers update for 4.5-rc1.

  Lots of gadget driver updates and fixes, like usual, and a mix of
  other USB driver updates as well.  Full details in the shortlog.  All
  of these have been in linux-next for a while"

* tag 'usb-4.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (191 commits)
  MAINTAINERS: change my email address
  USB: usbmon: remove assignment from IS_ERR argument
  USB: mxu11x0: drop redundant function name from error messages
  USB: mxu11x0: fix debug-message typos
  USB: mxu11x0: rename usb-serial driver
  USB: mxu11x0: fix modem-control handling on B0-transitions
  USB: mxu11x0: fix memory leak on firmware download
  USB: mxu11x0: fix memory leak in port-probe error path
  USB: serial: add Moxa UPORT 11x0 driver
  USB: cp210x: add ID for ELV Marble Sound Board 1
  usb: chipidea: otg: use usb autosuspend to suspend bus for HNP
  usb: chipidea: host: set host to be null after hcd is freed
  usb: chipidea: removing of_find_property
  usb: chipidea: implement platform shutdown callback
  usb: chipidea: clean up CONFIG_USB_CHIPIDEA_DEBUG reference
  usb: chipidea: delete static debug support
  usb: chipidea: support debugfs without CONFIG_USB_CHIPIDEA_DEBUG
  usb: chipidea: udc: improve error handling on _hardware_enqueue
  usb: chipidea: udc: _ep_queue and _hw_queue cleanup
  usb: dwc3: of-simple: fix build warning on !PM
  ...

5 files changed, 508 insertions, 116 deletions

diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
index 898a570319f1..fb1fe96d3215 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -23,6 +23,7 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/device.h>
+#include <linux/kfifo.h>
 
 #include <sound/core.h>
 #include <sound/initval.h>
@@ -75,6 +76,7 @@ struct f_midi {
 	struct usb_ep		*in_ep, *out_ep;
 	struct snd_card		*card;
 	struct snd_rawmidi	*rmidi;
+	u8			ms_id;
 
 	struct snd_rawmidi_substream *in_substream[MAX_PORTS];
 	struct snd_rawmidi_substream *out_substream[MAX_PORTS];
@@ -87,6 +89,9 @@ struct f_midi {
 	int index;
 	char *id;
 	unsigned int buflen, qlen;
+	/* This fifo is used as a buffer ring for pre-allocated IN usb_requests */
+	DECLARE_KFIFO_PTR(in_req_fifo, struct usb_request *);
+	unsigned int in_last_port;
 };
 
 static inline struct f_midi *func_to_midi(struct usb_function *f)
@@ -94,7 +99,7 @@ static inline struct f_midi *func_to_midi(struct usb_function *f)
 	return container_of(f, struct f_midi, func);
 }
 
-static void f_midi_transmit(struct f_midi *midi, struct usb_request *req);
+static void f_midi_transmit(struct f_midi *midi);
 
 DECLARE_UAC_AC_HEADER_DESCRIPTOR(1);
 DECLARE_USB_MIDI_OUT_JACK_DESCRIPTOR(1);
@@ -201,12 +206,6 @@ static inline struct usb_request *midi_alloc_ep_req(struct usb_ep *ep,
 	return alloc_ep_req(ep, length, length);
 }
 
-static void free_ep_req(struct usb_ep *ep, struct usb_request *req)
-{
-	kfree(req->buf);
-	usb_ep_free_request(ep, req);
-}
-
 static const uint8_t f_midi_cin_length[] = {
 	0, 0, 2, 3, 3, 1, 2, 3, 3, 3, 3, 3, 2, 2, 3, 1
 };
@@ -258,7 +257,8 @@ f_midi_complete(struct usb_ep *ep, struct usb_request *req)
 		} else if (ep == midi->in_ep) {
 			/* Our transmit completed. See if there's more to go.
 			 * f_midi_transmit eats req, don't queue it again. */
-			f_midi_transmit(midi, req);
+			req->length = 0;
+			f_midi_transmit(midi);
 			return;
 		}
 		break;
@@ -269,10 +269,12 @@ f_midi_complete(struct usb_ep *ep, struct usb_request *req)
 	case -ESHUTDOWN:	/* disconnect from host */
 		VDBG(cdev, "%s gone (%d), %d/%d\n", ep->name, status,
 				req->actual, req->length);
-		if (ep == midi->out_ep)
+		if (ep == midi->out_ep) {
 			f_midi_handle_out_data(ep, req);
-
-		free_ep_req(ep, req);
+			/* We don't need to free IN requests because it's handled
+			 * by the midi->in_req_fifo. */
+			free_ep_req(ep, req);
+		}
 		return;
 
 	case -EOVERFLOW:	/* buffer overrun on read means that
@@ -324,12 +326,11 @@ static int f_midi_start_ep(struct f_midi *midi,
 static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 {
 	struct f_midi *midi = func_to_midi(f);
-	struct usb_composite_dev *cdev = f->config->cdev;
 	unsigned i;
 	int err;
 
-	/* For Control Device interface we do nothing */
-	if (intf == 0)
+	/* we only set alt for MIDIStreaming interface */
+	if (intf != midi->ms_id)
 		return 0;
 
 	err = f_midi_start_ep(midi, f, midi->in_ep);
@@ -340,23 +341,19 @@ static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 	if (err)
 		return err;
 
-	usb_ep_disable(midi->out_ep);
+	/* pre-allocate write usb requests to use on f_midi_transmit. */
+	while (kfifo_avail(&midi->in_req_fifo)) {
+		struct usb_request *req =
+			midi_alloc_ep_req(midi->in_ep, midi->buflen);
 
-	err = config_ep_by_speed(midi->gadget, f, midi->out_ep);
-	if (err) {
-		ERROR(cdev, "can't configure %s: %d\n",
-		      midi->out_ep->name, err);
-		return err;
-	}
+		if (req == NULL)
+			return -ENOMEM;
 
-	err = usb_ep_enable(midi->out_ep);
-	if (err) {
-		ERROR(cdev, "can't start %s: %d\n",
-		      midi->out_ep->name, err);
-		return err;
-	}
+		req->length = 0;
+		req->complete = f_midi_complete;
 
-	midi->out_ep->driver_data = midi;
+		kfifo_put(&midi->in_req_fifo, req);
+	}
 
 	/* allocate a bunch of read buffers and queue them all at once. */
 	for (i = 0; i < midi->qlen && err == 0; i++) {
@@ -368,9 +365,10 @@ static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 		req->complete = f_midi_complete;
 		err = usb_ep_queue(midi->out_ep, req, GFP_ATOMIC);
 		if (err) {
-			ERROR(midi, "%s queue req: %d\n",
+			ERROR(midi, "%s: couldn't enqueue request: %d\n",
 				    midi->out_ep->name, err);
 			free_ep_req(midi->out_ep, req);
+			return err;
 		}
 	}
 
@@ -381,6 +379,7 @@ static void f_midi_disable(struct usb_function *f)
 {
 	struct f_midi *midi = func_to_midi(f);
 	struct usb_composite_dev *cdev = f->config->cdev;
+	struct usb_request *req = NULL;
 
 	DBG(cdev, "disable\n");
 
@@ -390,6 +389,10 @@ static void f_midi_disable(struct usb_function *f)
 	 */
 	usb_ep_disable(midi->in_ep);
 	usb_ep_disable(midi->out_ep);
+
+	/* release IN requests */
+	while (kfifo_get(&midi->in_req_fifo, &req))
+		free_ep_req(midi->in_ep, req);
 }
 
 static int f_midi_snd_free(struct snd_device *device)
@@ -511,57 +514,113 @@ static void f_midi_transmit_byte(struct usb_request *req,
 	}
 }
 
-static void f_midi_transmit(struct f_midi *midi, struct usb_request *req)
+static void f_midi_drop_out_substreams(struct f_midi *midi)
 {
-	struct usb_ep *ep = midi->in_ep;
-	int i;
-
-	if (!ep)
-		return;
-
-	if (!req)
-		req = midi_alloc_ep_req(ep, midi->buflen);
-
-	if (!req) {
-		ERROR(midi, "%s: alloc_ep_request failed\n", __func__);
-		return;
-	}
-	req->length = 0;
-	req->complete = f_midi_complete;
+	unsigned int i;
 
 	for (i = 0; i < MAX_PORTS; i++) {
 		struct gmidi_in_port *port = midi->in_port[i];
 		struct snd_rawmidi_substream *substream = midi->in_substream[i];
 
-		if (!port || !port->active || !substream)
+		if (!port)
+			break;
+
+		if (!port->active || !substream)
 			continue;
 
-		while (req->length + 3 < midi->buflen) {
-			uint8_t b;
-			if (snd_rawmidi_transmit(substream, &b, 1) != 1) {
-				port->active = 0;
+		snd_rawmidi_drop_output(substream);
+	}
+}
+
+static void f_midi_transmit(struct f_midi *midi)
+{
+	struct usb_ep *ep = midi->in_ep;
+	bool active;
+
+	/* We only care about USB requests if IN endpoint is enabled */
+	if (!ep || !ep->enabled)
+		goto drop_out;
+
+	do {
+		struct usb_request *req = NULL;
+		unsigned int len, i;
+
+		active = false;
+
+		/* We peek the request in order to reuse it if it fails
+		 * to enqueue on its endpoint */
+		len = kfifo_peek(&midi->in_req_fifo, &req);
+		if (len != 1) {
+			ERROR(midi, "%s: Couldn't get usb request\n", __func__);
+			goto drop_out;
+		}
+
+		/* If buffer overrun, then we ignore this transmission.
+		 * IMPORTANT: This will cause the user-space rawmidi device to block until a) usb
+		 * requests have been completed or b) snd_rawmidi_write() times out. */
+		if (req->length > 0)
+			return;
+
+		for (i = midi->in_last_port; i < MAX_PORTS; i++) {
+			struct gmidi_in_port *port = midi->in_port[i];
+			struct snd_rawmidi_substream *substream = midi->in_substream[i];
+
+			if (!port) {
+				/* Reset counter when we reach the last available port */
+				midi->in_last_port = 0;
+				break;
+			}
+
+			if (!port->active || !substream)
+				continue;
+
+			while (req->length + 3 < midi->buflen) {
+				uint8_t b;
+
+				if (snd_rawmidi_transmit(substream, &b, 1) != 1) {
+					port->active = 0;
+					break;
+				}
+				f_midi_transmit_byte(req, port, b);
+			}
+
+			active = !!port->active;
+			/* Check if last port is still active, which means that
+			 * there is still data on that substream but this current
+			 * request run out of space. */
+			if (active) {
+				midi->in_last_port = i;
+				/* There is no need to re-iterate though midi ports. */
 				break;
 			}
-			f_midi_transmit_byte(req, port, b);
 		}
-	}
 
-	if (req->length > 0 && ep->enabled) {
-		int err;
+		if (req->length > 0) {
+			int err;
 
-		err = usb_ep_queue(ep, req, GFP_ATOMIC);
-		if (err < 0)
-			ERROR(midi, "%s queue req: %d\n",
-			      midi->in_ep->name, err);
-	} else {
-		free_ep_req(ep, req);
-	}
+			err = usb_ep_queue(ep, req, GFP_ATOMIC);
+			if (err < 0) {
+				ERROR(midi, "%s failed to queue req: %d\n",
+				      midi->in_ep->name, err);
+				req->length = 0; /* Re-use request next time. */
+			} else {
+				/* Upon success, put request at the back of the queue. */
+				kfifo_skip(&midi->in_req_fifo);
+				kfifo_put(&midi->in_req_fifo, req);
+			}
+		}
+	} while (active);
+
+	return;
+
+drop_out:
+	f_midi_drop_out_substreams(midi);
 }
 
 static void f_midi_in_tasklet(unsigned long data)
 {
 	struct f_midi *midi = (struct f_midi *) data;
-	f_midi_transmit(midi, NULL);
+	f_midi_transmit(midi);
 }
 
 static int f_midi_in_open(struct snd_rawmidi_substream *substream)
@@ -687,6 +746,7 @@ static int f_midi_register_card(struct f_midi *midi)
 		goto fail;
 	}
 	midi->rmidi = rmidi;
+	midi->in_last_port = 0;
 	strcpy(rmidi->name, card->shortname);
 	rmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
 			    SNDRV_RAWMIDI_INFO_INPUT |
@@ -755,6 +815,7 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f)
 		goto fail;
 	ms_interface_desc.bInterfaceNumber = status;
 	ac_header_desc.baInterfaceNr[0] = status;
+	midi->ms_id = status;
 
 	status = -ENODEV;
 
@@ -1075,6 +1136,7 @@ static void f_midi_free(struct usb_function *f)
 	mutex_lock(&opts->lock);
 	for (i = opts->in_ports - 1; i >= 0; --i)
 		kfree(midi->in_port[i]);
+	kfifo_free(&midi->in_req_fifo);
 	kfree(midi);
 	--opts->refcnt;
 	mutex_unlock(&opts->lock);
@@ -1148,6 +1210,12 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
 	midi->index = opts->index;
 	midi->buflen = opts->buflen;
 	midi->qlen = opts->qlen;
+	midi->in_last_port = 0;
+
+	status = kfifo_alloc(&midi->in_req_fifo, midi->qlen, GFP_KERNEL);
+	if (status)
+		goto setup_fail;
+
 	++opts->refcnt;
 	mutex_unlock(&opts->lock);
 
diff --git a/drivers/usb/gadget/function/f_sourcesink.c b/drivers/usb/gadget/function/f_sourcesink.c
index 9f3ced62d916..242ba5caffe5 100644
--- a/drivers/usb/gadget/function/f_sourcesink.c
+++ b/drivers/usb/gadget/function/f_sourcesink.c
@@ -34,13 +34,6 @@
  * plus two that support control-OUT tests.  If the optional "autoresume"
  * mode is enabled, it provides good functional coverage for the "USBCV"
  * test harness from USB-IF.
- *
- * Note that because this doesn't queue more than one request at a time,
- * some other function must be used to test queueing logic.  The network
- * link (g_ether) is the best overall option for that, since its TX and RX
- * queues are relatively independent, will receive a range of packet sizes,
- * and can often be made to run out completely.  Those issues are important
- * when stress testing peripheral controller drivers.
  */
 struct f_sourcesink {
 	struct usb_function	function;
@@ -57,6 +50,8 @@ struct f_sourcesink {
 	unsigned isoc_mult;
 	unsigned isoc_maxburst;
 	unsigned buflen;
+	unsigned bulk_qlen;
+	unsigned iso_qlen;
 };
 
 static inline struct f_sourcesink *func_to_ss(struct usb_function *f)
@@ -303,12 +298,6 @@ static inline struct usb_request *ss_alloc_ep_req(struct usb_ep *ep, int len)
 	return alloc_ep_req(ep, len, ss->buflen);
 }
 
-void free_ep_req(struct usb_ep *ep, struct usb_request *req)
-{
-	kfree(req->buf);
-	usb_ep_free_request(ep, req);
-}
-
 static void disable_ep(struct usb_composite_dev *cdev, struct usb_ep *ep)
 {
 	int			value;
@@ -595,31 +584,33 @@ static int source_sink_start_ep(struct f_sourcesink *ss, bool is_in,
 {
 	struct usb_ep		*ep;
 	struct usb_request	*req;
-	int			i, size, status;
-
-	for (i = 0; i < 8; i++) {
-		if (is_iso) {
-			switch (speed) {
-			case USB_SPEED_SUPER:
-				size = ss->isoc_maxpacket *
-						(ss->isoc_mult + 1) *
-						(ss->isoc_maxburst + 1);
-				break;
-			case USB_SPEED_HIGH:
-				size = ss->isoc_maxpacket * (ss->isoc_mult + 1);
-				break;
-			default:
-				size = ss->isoc_maxpacket > 1023 ?
-						1023 : ss->isoc_maxpacket;
-				break;
-			}
-			ep = is_in ? ss->iso_in_ep : ss->iso_out_ep;
-			req = ss_alloc_ep_req(ep, size);
-		} else {
-			ep = is_in ? ss->in_ep : ss->out_ep;
-			req = ss_alloc_ep_req(ep, 0);
+	int			i, size, qlen, status = 0;
+
+	if (is_iso) {
+		switch (speed) {
+		case USB_SPEED_SUPER:
+			size = ss->isoc_maxpacket *
+					(ss->isoc_mult + 1) *
+					(ss->isoc_maxburst + 1);
+			break;
+		case USB_SPEED_HIGH:
+			size = ss->isoc_maxpacket * (ss->isoc_mult + 1);
+			break;
+		default:
+			size = ss->isoc_maxpacket > 1023 ?
+					1023 : ss->isoc_maxpacket;
+			break;
 		}
+		ep = is_in ? ss->iso_in_ep : ss->iso_out_ep;
+		qlen = ss->iso_qlen;
+	} else {
+		ep = is_in ? ss->in_ep : ss->out_ep;
+		qlen = ss->bulk_qlen;
+		size = 0;
+	}
 
+	for (i = 0; i < qlen; i++) {
+		req = ss_alloc_ep_req(ep, size);
 		if (!req)
 			return -ENOMEM;
 
@@ -638,10 +629,8 @@ static int source_sink_start_ep(struct f_sourcesink *ss, bool is_in,
 			      is_iso ? "ISO-" : "", is_in ? "IN" : "OUT",
 			      ep->name, status);
 			free_ep_req(ep, req);
+			return status;
 		}
-
-		if (!is_iso)
-			break;
 	}
 
 	return status;
@@ -869,6 +858,8 @@ static struct usb_function *source_sink_alloc_func(
 	ss->isoc_mult = ss_opts->isoc_mult;
 	ss->isoc_maxburst = ss_opts->isoc_maxburst;
 	ss->buflen = ss_opts->bulk_buflen;
+	ss->bulk_qlen = ss_opts->bulk_qlen;
+	ss->iso_qlen = ss_opts->iso_qlen;
 
 	ss->function.name = "source/sink";
 	ss->function.bind = sourcesink_bind;
@@ -1153,6 +1144,82 @@ end:
 
 CONFIGFS_ATTR(f_ss_opts_, bulk_buflen);
 
+static ssize_t f_ss_opts_bulk_qlen_show(struct config_item *item, char *page)
+{
+	struct f_ss_opts *opts = to_f_ss_opts(item);
+	int result;
+
+	mutex_lock(&opts->lock);
+	result = sprintf(page, "%u\n", opts->bulk_qlen);
+	mutex_unlock(&opts->lock);
+
+	return result;
+}
+
+static ssize_t f_ss_opts_bulk_qlen_store(struct config_item *item,
+					   const char *page, size_t len)
+{
+	struct f_ss_opts *opts = to_f_ss_opts(item);
+	int ret;
+	u32 num;
+
+	mutex_lock(&opts->lock);
+	if (opts->refcnt) {
+		ret = -EBUSY;
+		goto end;
+	}
+
+	ret = kstrtou32(page, 0, &num);
+	if (ret)
+		goto end;
+
+	opts->bulk_qlen = num;
+	ret = len;
+end:
+	mutex_unlock(&opts->lock);
+	return ret;
+}
+
+CONFIGFS_ATTR(f_ss_opts_, bulk_qlen);
+
+static ssize_t f_ss_opts_iso_qlen_show(struct config_item *item, char *page)
+{
+	struct f_ss_opts *opts = to_f_ss_opts(item);
+	int result;
+
+	mutex_lock(&opts->lock);
+	result = sprintf(page, "%u\n", opts->iso_qlen);
+	mutex_unlock(&opts->lock);
+
+	return result;
+}
+
+static ssize_t f_ss_opts_iso_qlen_store(struct config_item *item,
+					   const char *page, size_t len)
+{
+	struct f_ss_opts *opts = to_f_ss_opts(item);
+	int ret;
+	u32 num;
+
+	mutex_lock(&opts->lock);
+	if (opts->refcnt) {
+		ret = -EBUSY;
+		goto end;
+	}
+
+	ret = kstrtou32(page, 0, &num);
+	if (ret)
+		goto end;
+
+	opts->iso_qlen = num;
+	ret = len;
+end:
+	mutex_unlock(&opts->lock);
+	return ret;
+}
+
+CONFIGFS_ATTR(f_ss_opts_, iso_qlen);
+
 static struct configfs_attribute *ss_attrs[] = {
 	&f_ss_opts_attr_pattern,
 	&f_ss_opts_attr_isoc_interval,
@@ -1160,6 +1227,8 @@ static struct configfs_attribute *ss_attrs[] = {
 	&f_ss_opts_attr_isoc_mult,
 	&f_ss_opts_attr_isoc_maxburst,
 	&f_ss_opts_attr_bulk_buflen,
+	&f_ss_opts_attr_bulk_qlen,
+	&f_ss_opts_attr_iso_qlen,
 	NULL,
 };
 
@@ -1189,6 +1258,8 @@ static struct usb_function_instance *source_sink_alloc_inst(void)
 	ss_opts->isoc_interval = GZERO_ISOC_INTERVAL;
 	ss_opts->isoc_maxpacket = GZERO_ISOC_MAXPACKET;
 	ss_opts->bulk_buflen = GZERO_BULK_BUFLEN;
+	ss_opts->bulk_qlen = GZERO_SS_BULK_QLEN;
+	ss_opts->iso_qlen = GZERO_SS_ISO_QLEN;
 
 	config_group_init_type_name(&ss_opts->func_inst.group, "",
 				    &ss_func_type);
diff --git a/drivers/usb/gadget/function/g_zero.h b/drivers/usb/gadget/function/g_zero.h
index 15f180904f8a..492924d0d599 100644
--- a/drivers/usb/gadget/function/g_zero.h
+++ b/drivers/usb/gadget/function/g_zero.h
@@ -10,6 +10,8 @@
 #define GZERO_QLEN		32
 #define GZERO_ISOC_INTERVAL	4
 #define GZERO_ISOC_MAXPACKET	1024
+#define GZERO_SS_BULK_QLEN	1
+#define GZERO_SS_ISO_QLEN	8
 
 struct usb_zero_options {
 	unsigned pattern;
@@ -19,6 +21,8 @@ struct usb_zero_options {
 	unsigned isoc_maxburst;
 	unsigned bulk_buflen;
 	unsigned qlen;
+	unsigned ss_bulk_qlen;
+	unsigned ss_iso_qlen;
 };
 
 struct f_ss_opts {
@@ -29,6 +33,8 @@ struct f_ss_opts {
 	unsigned isoc_mult;
 	unsigned isoc_maxburst;
 	unsigned bulk_buflen;
+	unsigned bulk_qlen;
+	unsigned iso_qlen;
 
 	/*
 	 * Read/write access to configfs attributes is handled by configfs.
@@ -59,7 +65,6 @@ void lb_modexit(void);
 int lb_modinit(void);
 
 /* common utilities */
-void free_ep_req(struct usb_ep *ep, struct usb_request *req);
 void disable_endpoints(struct usb_composite_dev *cdev,
 		struct usb_ep *in, struct usb_ep *out,
 		struct usb_ep *iso_in, struct usb_ep *iso_out);
diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c
index 6554322af2c1..637809e3bd0d 100644
--- a/drivers/usb/gadget/function/u_ether.c
+++ b/drivers/usb/gadget/function/u_ether.c
@@ -143,21 +143,11 @@ static inline int qlen(struct usb_gadget *gadget, unsigned qmult)
 
 static int ueth_change_mtu(struct net_device *net, int new_mtu)
 {
-	struct eth_dev	*dev = netdev_priv(net);
-	unsigned long	flags;
-	int		status = 0;
+	if (new_mtu <= ETH_HLEN || new_mtu > GETHER_MAX_ETH_FRAME_LEN)
+		return -ERANGE;
+	net->mtu = new_mtu;
 
-	/* don't change MTU on "live" link (peer won't know) */
-	spin_lock_irqsave(&dev->lock, flags);
-	if (dev->port_usb)
-		status = -EBUSY;
-	else if (new_mtu <= ETH_HLEN || new_mtu > GETHER_MAX_ETH_FRAME_LEN)
-		status = -ERANGE;
-	else
-		net->mtu = new_mtu;
-	spin_unlock_irqrestore(&dev->lock, flags);
-
-	return status;
+	return 0;
 }
 
 static void eth_get_drvinfo(struct net_device *net, struct ethtool_drvinfo *p)
diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index f7771d86ad6c..6af145f2a99d 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -27,6 +27,8 @@
 #include <linux/slab.h>
 #include <linux/export.h>
 #include <linux/module.h>
+#include <linux/console.h>
+#include <linux/kthread.h>
 
 #include "u_serial.h"
 
@@ -79,6 +81,7 @@
  */
 #define QUEUE_SIZE		16
 #define WRITE_BUF_SIZE		8192		/* TX only */
+#define GS_CONSOLE_BUF_SIZE	8192
 
 /* circular buffer */
 struct gs_buf {
@@ -88,6 +91,17 @@ struct gs_buf {
 	char			*buf_put;
 };
 
+/* console info */
+struct gscons_info {
+	struct gs_port		*port;
+	struct task_struct	*console_thread;
+	struct gs_buf		con_buf;
+	/* protect the buf and busy flag */
+	spinlock_t		con_lock;
+	int			req_busy;
+	struct usb_request	*console_req;
+};
+
 /*
  * The port structure holds info for each port, one for each minor number
  * (and thus for each /dev/ node).
@@ -1023,6 +1037,246 @@ static const struct tty_operations gs_tty_ops = {
 
 static struct tty_driver *gs_tty_driver;
 
+#ifdef CONFIG_U_SERIAL_CONSOLE
+
+static struct gscons_info gscons_info;
+static struct console gserial_cons;
+
+static struct usb_request *gs_request_new(struct usb_ep *ep)
+{
+	struct usb_request *req = usb_ep_alloc_request(ep, GFP_ATOMIC);
+	if (!req)
+		return NULL;
+
+	req->buf = kmalloc(ep->maxpacket, GFP_ATOMIC);
+	if (!req->buf) {
+		usb_ep_free_request(ep, req);
+		return NULL;
+	}
+
+	return req;
+}
+
+static void gs_request_free(struct usb_request *req, struct usb_ep *ep)
+{
+	if (!req)
+		return;
+
+	kfree(req->buf);
+	usb_ep_free_request(ep, req);
+}
+
+static void gs_complete_out(struct usb_ep *ep, struct usb_request *req)
+{
+	struct gscons_info *info = &gscons_info;
+
+	switch (req->status) {
+	default:
+		pr_warn("%s: unexpected %s status %d\n",
+			__func__, ep->name, req->status);
+	case 0:
+		/* normal completion */
+		spin_lock(&info->con_lock);
+		info->req_busy = 0;
+		spin_unlock(&info->con_lock);
+
+		wake_up_process(info->console_thread);
+		break;
+	case -ESHUTDOWN:
+		/* disconnect */
+		pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
+		break;
+	}
+}
+
+static int gs_console_connect(int port_num)
+{
+	struct gscons_info *info = &gscons_info;
+	struct gs_port *port;
+	struct usb_ep *ep;
+
+	if (port_num != gserial_cons.index) {
+		pr_err("%s: port num [%d] is not support console\n",
+		       __func__, port_num);
+		return -ENXIO;
+	}
+
+	port = ports[port_num].port;
+	ep = port->port_usb->in;
+	if (!info->console_req) {
+		info->console_req = gs_request_new(ep);
+		if (!info->console_req)
+			return -ENOMEM;
+		info->console_req->complete = gs_complete_out;
+	}
+
+	info->port = port;
+	spin_lock(&info->con_lock);
+	info->req_busy = 0;
+	spin_unlock(&info->con_lock);
+	pr_vdebug("port[%d] console connect!\n", port_num);
+	return 0;
+}
+
+static void gs_console_disconnect(struct usb_ep *ep)
+{
+	struct gscons_info *info = &gscons_info;
+	struct usb_request *req = info->console_req;
+
+	gs_request_free(req, ep);
+	info->console_req = NULL;
+}
+
+static int gs_console_thread(void *data)
+{
+	struct gscons_info *info = &gscons_info;
+	struct gs_port *port;
+	struct usb_request *req;
+	struct usb_ep *ep;
+	int xfer, ret, count, size;
+
+	do {
+		port = info->port;
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (!port || !port->port_usb
+		    || !port->port_usb->in || !info->console_req)
+			goto sched;
+
+		req = info->console_req;
+		ep = port->port_usb->in;
+
+		spin_lock_irq(&info->con_lock);
+		count = gs_buf_data_avail(&info->con_buf);
+		size = ep->maxpacket;
+
+		if (count > 0 && !info->req_busy) {
+			set_current_state(TASK_RUNNING);
+			if (count < size)
+				size = count;
+
+			xfer = gs_buf_get(&info->con_buf, req->buf, size);
+			req->length = xfer;
+
+			spin_unlock(&info->con_lock);
+			ret = usb_ep_queue(ep, req, GFP_ATOMIC);
+			spin_lock(&info->con_lock);
+			if (ret < 0)
+				info->req_busy = 0;
+			else
+				info->req_busy = 1;
+
+			spin_unlock_irq(&info->con_lock);
+		} else {
+			spin_unlock_irq(&info->con_lock);
+sched:
+			if (kthread_should_stop()) {
+				set_current_state(TASK_RUNNING);
+				break;
+			}
+			schedule();
+		}
+	} while (1);
+
+	return 0;
+}
+
+static int gs_console_setup(struct console *co, char *options)
+{
+	struct gscons_info *info = &gscons_info;
+	int status;
+
+	info->port = NULL;
+	info->console_req = NULL;
+	info->req_busy = 0;
+	spin_lock_init(&info->con_lock);
+
+	status = gs_buf_alloc(&info->con_buf, GS_CONSOLE_BUF_SIZE);
+	if (status) {
+		pr_err("%s: allocate console buffer failed\n", __func__);
+		return status;
+	}
+
+	info->console_thread = kthread_create(gs_console_thread,
+					      co, "gs_console");
+	if (IS_ERR(info->console_thread)) {
+		pr_err("%s: cannot create console thread\n", __func__);
+		gs_buf_free(&info->con_buf);
+		return PTR_ERR(info->console_thread);
+	}
+	wake_up_process(info->console_thread);
+
+	return 0;
+}
+
+static void gs_console_write(struct console *co,
+			     const char *buf, unsigned count)
+{
+	struct gscons_info *info = &gscons_info;
+	unsigned long flags;
+
+	spin_lock_irqsave(&info->con_lock, flags);
+	gs_buf_put(&info->con_buf, buf, count);
+	spin_unlock_irqrestore(&info->con_lock, flags);
+
+	wake_up_process(info->console_thread);
+}
+
+static struct tty_driver *gs_console_device(struct console *co, int *index)
+{
+	struct tty_driver **p = (struct tty_driver **)co->data;
+
+	if (!*p)
+		return NULL;
+
+	*index = co->index;
+	return *p;
+}
+
+static struct console gserial_cons = {
+	.name =		"ttyGS",
+	.write =	gs_console_write,
+	.device =	gs_console_device,
+	.setup =	gs_console_setup,
+	.flags =	CON_PRINTBUFFER,
+	.index =	-1,
+	.data =		&gs_tty_driver,
+};
+
+static void gserial_console_init(void)
+{
+	register_console(&gserial_cons);
+}
+
+static void gserial_console_exit(void)
+{
+	struct gscons_info *info = &gscons_info;
+
+	unregister_console(&gserial_cons);
+	kthread_stop(info->console_thread);
+	gs_buf_free(&info->con_buf);
+}
+
+#else
+
+static int gs_console_connect(int port_num)
+{
+	return 0;
+}
+
+static void gs_console_disconnect(struct usb_ep *ep)
+{
+}
+
+static void gserial_console_init(void)
+{
+}
+
+static void gserial_console_exit(void)
+{
+}
+
+#endif
+
 static int
 gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)
 {
@@ -1096,6 +1350,7 @@ void gserial_free_line(unsigned char port_num)
 
 	gserial_free_port(port);
 	tty_unregister_device(gs_tty_driver, port_num);
+	gserial_console_exit();
 }
 EXPORT_SYMBOL_GPL(gserial_free_line);
 
@@ -1138,6 +1393,7 @@ int gserial_alloc_line(unsigned char *line_num)
 		goto err;
 	}
 	*line_num = port_num;
+	gserial_console_init();
 err:
 	return ret;
 }
@@ -1219,6 +1475,7 @@ int gserial_connect(struct gserial *gser, u8 port_num)
 			gser->disconnect(gser);
 	}
 
+	status = gs_console_connect(port_num);
 	spin_unlock_irqrestore(&port->port_lock, flags);
 
 	return status;
@@ -1277,6 +1534,7 @@ void gserial_disconnect(struct gserial *gser)
 	port->read_allocated = port->read_started =
 		port->write_allocated = port->write_started = 0;
 
+	gs_console_disconnect(gser->in);
 	spin_unlock_irqrestore(&port->port_lock, flags);
 }
 EXPORT_SYMBOL_GPL(gserial_disconnect);