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[PATCH v4 00/10] Gadget endpoint request allocation and MIDI

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  [PATCH v4 00/10] Gadget endpoint request allocation and MIDI "Felipe F. Tonello" <eu@felipetonello.com> - 2016-08-08 22:40 +0200
    [PATCH v4 04/10] usb: gadget: f_midi: remove alignment code for OUT endpoint "Felipe F. Tonello" <eu@felipetonello.com> - 2016-08-08 22:40 +0200
    [PATCH v4 03/10] usb: gadget: align buffer size when allocating for OUT endpoint "Felipe F. Tonello" <eu@felipetonello.com> - 2016-08-08 22:40 +0200
    [PATCH v4 02/10] usb: gadget: change len to size_t on alloc_ep_req() "Felipe F. Tonello" <eu@felipetonello.com> - 2016-08-08 22:40 +0200
    [PATCH v4 06/10] usb: gadget: f_midi: refactor state machine "Felipe F. Tonello" <eu@felipetonello.com> - 2016-08-08 22:40 +0200
    [PATCH v4 09/10] usb: gadget: f_hid: use free_ep_req() "Felipe F. Tonello" <eu@felipetonello.com> - 2016-08-08 22:40 +0200
    [PATCH v4 10/10] usb: gadget: f_hid: use alloc_ep_req() "Felipe F. Tonello" <eu@felipetonello.com> - 2016-08-08 22:40 +0200
    [PATCH v4 05/10] usb: gadget: f_midi: defaults buflen sizes to 512 "Felipe F. Tonello" <eu@felipetonello.com> - 2016-08-08 22:40 +0200

#1458223 — [PATCH v4 00/10] Gadget endpoint request allocation and MIDI

As discussed with Baolin Wang, Michal Nazarewicz and Felipe Balbi. I propose
the forced buffer alignment of OUT endpoints USB requests. This is implemented
by patches #1 and #3.

That not just simplifies the driver code, but it also prevents nasty bugs when
buflen is not aligned or even less than wMaxPacketSize.

Patch #10 removes direct calls to usb_ep_alloc_request() and use alloc_ep_req()
instead. If accepted, then we should apply to all other gadgets that uses
usb_ep_alloc_request() when possible and encorage drivers to use it instead.

Changes from v3:
 * Added patch #2 which uses size_t on alloc_ep_req() instead of int.

Changes from v2:
 * Simplified logic in patch #1;
 * Added documentation to alloc_ep_req and free_ep_req;
 * Improved commit message on patch #8.

Changes from v1:
 * Added patches #1, #3, #8, #9 ,#10;
 * Patch #4 removes max_t() for buffer alignment with wMaxPacketSize.

Felipe F. Tonello (10):
  usb: gadget: fix usb_ep_align_maybe endianness and new usb_ep_align
  usb: gadget: change len to size_t on alloc_ep_req()
  usb: gadget: align buffer size when allocating for OUT endpoint
  usb: gadget: f_midi: remove alignment code for OUT endpoint
  usb: gadget: f_midi: defaults buflen sizes to 512
  usb: gadget: f_midi: refactor state machine
  usb: gadget: f_midi: drop substreams when disabling endpoint
  usb: gadget: remove useless parameter in alloc_ep_req()
  usb: gadget: f_hid: use free_ep_req()
  usb: gadget: f_hid: use alloc_ep_req()

 drivers/usb/gadget/function/f_hid.c        |  26 +---
 drivers/usb/gadget/function/f_loopback.c   |   9 +-
 drivers/usb/gadget/function/f_midi.c       | 240 +++++++++++++++++------------
 drivers/usb/gadget/function/f_sourcesink.c |  11 +-
 drivers/usb/gadget/legacy/gmidi.c          |   2 +-
 drivers/usb/gadget/u_f.c                   |   6 +-
 drivers/usb/gadget/u_f.h                   |  17 +-
 include/linux/usb/gadget.h                 |  17 +-
 8 files changed, 188 insertions(+), 140 deletions(-)

-- 
2.9.2

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#1458224 — [PATCH v4 04/10] usb: gadget: f_midi: remove alignment code for OUT endpoint

The new version of alloc_ep_req() already aligns the buffer size to
wMaxPacketSize on OUT endpoints.

Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
---
 drivers/usb/gadget/function/f_midi.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
index 58fc199a18ec..39018dea7035 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -360,9 +360,8 @@ static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 	/* allocate a bunch of read buffers and queue them all at once. */
 	for (i = 0; i < midi->qlen && err == 0; i++) {
 		struct usb_request *req =
-			midi_alloc_ep_req(midi->out_ep,
-				max_t(unsigned, midi->buflen,
-					bulk_out_desc.wMaxPacketSize));
+			midi_alloc_ep_req(midi->out_ep, midi->buflen);
+
 		if (req == NULL)
 			return -ENOMEM;
 
-- 
2.9.2

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#1458227 — [PATCH v4 03/10] usb: gadget: align buffer size when allocating for OUT endpoint

Using usb_ep_align() makes sure that the buffer size for OUT endpoints is
always aligned with wMaxPacketSize (512 usually). This makes sure
that no buffer has the wrong size, which can cause nasty bugs.

Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
---
 drivers/usb/gadget/u_f.c |  3 +++
 drivers/usb/gadget/u_f.h | 16 +++++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/u_f.c b/drivers/usb/gadget/u_f.c
index 6811761fec64..907f8144813c 100644
--- a/drivers/usb/gadget/u_f.c
+++ b/drivers/usb/gadget/u_f.c
@@ -12,6 +12,7 @@
  */
 
 #include "u_f.h"
+#include <linux/usb/ch9.h>
 
 struct usb_request *alloc_ep_req(struct usb_ep *ep, size_t len, int default_len)
 {
@@ -20,6 +21,8 @@ struct usb_request *alloc_ep_req(struct usb_ep *ep, size_t len, int default_len)
 	req = usb_ep_alloc_request(ep, GFP_ATOMIC);
 	if (req) {
 		req->length = len ?: default_len;
+		if (usb_endpoint_dir_out(ep->desc))
+			req->length = usb_ep_align(ep, req->length);
 		req->buf = kmalloc(req->length, GFP_ATOMIC);
 		if (!req->buf) {
 			usb_ep_free_request(ep, req);
diff --git a/drivers/usb/gadget/u_f.h b/drivers/usb/gadget/u_f.h
index 21b75710c4a4..69a1d10df04f 100644
--- a/drivers/usb/gadget/u_f.h
+++ b/drivers/usb/gadget/u_f.h
@@ -47,8 +47,22 @@
 struct usb_ep;
 struct usb_request;
 
-/* Requests allocated via alloc_ep_req() must be freed by free_ep_req(). */
+/**
+ * alloc_ep_req - returns a usb_request allocated by the gadget driver and
+ * allocates the request's buffer.
+ *
+ * @ep: the endpoint to allocate a usb_request
+ * @len: usb_requests's buffer suggested size
+ * @default_len: used if @len is not provided, ie, is 0
+ *
+ * In case @ep direction is OUT, the @len will be aligned to ep's
+ * wMaxPacketSize. In order to avoid memory leaks or drops, *always* use
+ * usb_requests's length (req->length) to refer to the allocated buffer size.
+ * Requests allocated via alloc_ep_req() *must* be freed by free_ep_req().
+ */
 struct usb_request *alloc_ep_req(struct usb_ep *ep, size_t len, int default_len);
+
+/* Frees a usb_request previously allocated by alloc_ep_req() */
 static inline void free_ep_req(struct usb_ep *ep, struct usb_request *req)
 {
 	kfree(req->buf);
-- 
2.9.2

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#1458229 — [PATCH v4 02/10] usb: gadget: change len to size_t on alloc_ep_req()

Length of buffers should be of type size_t whenever possible. Altough
recommended, this change has no real practical change, unless a driver has a
uses a huge or negative buffer size - it might help find these bugs.

Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
---
 drivers/usb/gadget/u_f.c | 2 +-
 drivers/usb/gadget/u_f.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/u_f.c b/drivers/usb/gadget/u_f.c
index 4bc7eea8bfc8..6811761fec64 100644
--- a/drivers/usb/gadget/u_f.c
+++ b/drivers/usb/gadget/u_f.c
@@ -13,7 +13,7 @@
 
 #include "u_f.h"
 
-struct usb_request *alloc_ep_req(struct usb_ep *ep, int len, int default_len)
+struct usb_request *alloc_ep_req(struct usb_ep *ep, size_t len, int default_len)
 {
 	struct usb_request      *req;
 
diff --git a/drivers/usb/gadget/u_f.h b/drivers/usb/gadget/u_f.h
index 4247cc098a89..21b75710c4a4 100644
--- a/drivers/usb/gadget/u_f.h
+++ b/drivers/usb/gadget/u_f.h
@@ -48,7 +48,7 @@ struct usb_ep;
 struct usb_request;
 
 /* Requests allocated via alloc_ep_req() must be freed by free_ep_req(). */
-struct usb_request *alloc_ep_req(struct usb_ep *ep, int len, int default_len);
+struct usb_request *alloc_ep_req(struct usb_ep *ep, size_t len, int default_len);
 static inline void free_ep_req(struct usb_ep *ep, struct usb_request *req)
 {
 	kfree(req->buf);
-- 
2.9.2

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#1458230 — [PATCH v4 06/10] usb: gadget: f_midi: refactor state machine

This refactor results in a cleaner state machine code and promotes
consistency, readability, and maintanability of this driver.

This refactor state machine was well tested and it is currently running in
production code and devices.

Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
---
 drivers/usb/gadget/function/f_midi.c | 204 ++++++++++++++++++++++-------------
 1 file changed, 129 insertions(+), 75 deletions(-)

diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
index a7b50ac947f8..09d769e18b50 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -51,6 +51,19 @@ static const char f_midi_longname[] = "MIDI Gadget";
  */
 #define MAX_PORTS 16
 
+/* MIDI message states */
+enum {
+	STATE_INITIAL = 0,	/* pseudo state */
+	STATE_1PARAM,
+	STATE_2PARAM_1,
+	STATE_2PARAM_2,
+	STATE_SYSEX_0,
+	STATE_SYSEX_1,
+	STATE_SYSEX_2,
+	STATE_REAL_TIME,
+	STATE_FINISHED,		/* pseudo state */
+};
+
 /*
  * This is a gadget, and the IN/OUT naming is from the host's perspective.
  * USB -> OUT endpoint -> rawmidi
@@ -61,13 +74,6 @@ struct gmidi_in_port {
 	int active;
 	uint8_t cable;
 	uint8_t state;
-#define STATE_UNKNOWN	0
-#define STATE_1PARAM	1
-#define STATE_2PARAM_1	2
-#define STATE_2PARAM_2	3
-#define STATE_SYSEX_0	4
-#define STATE_SYSEX_1	5
-#define STATE_SYSEX_2	6
 	uint8_t data[2];
 };
 
@@ -403,118 +409,166 @@ static int f_midi_snd_free(struct snd_device *device)
 	return 0;
 }
 
-static void f_midi_transmit_packet(struct usb_request *req, uint8_t p0,
-					uint8_t p1, uint8_t p2, uint8_t p3)
-{
-	unsigned length = req->length;
-	u8 *buf = (u8 *)req->buf + length;
-
-	buf[0] = p0;
-	buf[1] = p1;
-	buf[2] = p2;
-	buf[3] = p3;
-	req->length = length + 4;
-}
-
 /*
  * Converts MIDI commands to USB MIDI packets.
  */
 static void f_midi_transmit_byte(struct usb_request *req,
 				 struct gmidi_in_port *port, uint8_t b)
 {
-	uint8_t p0 = port->cable << 4;
+	uint8_t p[4] = { port->cable << 4, 0, 0, 0 };
+	uint8_t next_state = STATE_INITIAL;
+
+	switch (b) {
+	case 0xf8 ... 0xff:
+		/* System Real-Time Messages */
+		p[0] |= 0x0f;
+		p[1] = b;
+		next_state = port->state;
+		port->state = STATE_REAL_TIME;
+		break;
+
+	case 0xf7:
+		/* End of SysEx */
+		switch (port->state) {
+		case STATE_SYSEX_0:
+			p[0] |= 0x05;
+			p[1] = 0xf7;
+			next_state = STATE_FINISHED;
+			break;
+		case STATE_SYSEX_1:
+			p[0] |= 0x06;
+			p[1] = port->data[0];
+			p[2] = 0xf7;
+			next_state = STATE_FINISHED;
+			break;
+		case STATE_SYSEX_2:
+			p[0] |= 0x07;
+			p[1] = port->data[0];
+			p[2] = port->data[1];
+			p[3] = 0xf7;
+			next_state = STATE_FINISHED;
+			break;
+		default:
+			/* Ignore byte */
+			next_state = port->state;
+			port->state = STATE_INITIAL;
+		}
+		break;
 
-	if (b >= 0xf8) {
-		f_midi_transmit_packet(req, p0 | 0x0f, b, 0, 0);
-	} else if (b >= 0xf0) {
+	case 0xf0 ... 0xf6:
+		/* System Common Messages */
+		port->data[0] = port->data[1] = 0;
+		port->state = STATE_INITIAL;
 		switch (b) {
 		case 0xf0:
 			port->data[0] = b;
-			port->state = STATE_SYSEX_1;
+			port->data[1] = 0;
+			next_state = STATE_SYSEX_1;
 			break;
 		case 0xf1:
 		case 0xf3:
 			port->data[0] = b;
-			port->state = STATE_1PARAM;
+			next_state = STATE_1PARAM;
 			break;
 		case 0xf2:
 			port->data[0] = b;
-			port->state = STATE_2PARAM_1;
+			next_state = STATE_2PARAM_1;
 			break;
 		case 0xf4:
 		case 0xf5:
-			port->state = STATE_UNKNOWN;
+			next_state = STATE_INITIAL;
 			break;
 		case 0xf6:
-			f_midi_transmit_packet(req, p0 | 0x05, 0xf6, 0, 0);
-			port->state = STATE_UNKNOWN;
-			break;
-		case 0xf7:
-			switch (port->state) {
-			case STATE_SYSEX_0:
-				f_midi_transmit_packet(req,
-					p0 | 0x05, 0xf7, 0, 0);
-				break;
-			case STATE_SYSEX_1:
-				f_midi_transmit_packet(req,
-					p0 | 0x06, port->data[0], 0xf7, 0);
-				break;
-			case STATE_SYSEX_2:
-				f_midi_transmit_packet(req,
-					p0 | 0x07, port->data[0],
-					port->data[1], 0xf7);
-				break;
-			}
-			port->state = STATE_UNKNOWN;
+			p[0] |= 0x05;
+			p[1] = 0xf6;
+			next_state = STATE_FINISHED;
 			break;
 		}
-	} else if (b >= 0x80) {
+		break;
+
+	case 0x80 ... 0xef:
+		/*
+		 * Channel Voice Messages, Channel Mode Messages
+		 * and Control Change Messages.
+		 */
 		port->data[0] = b;
+		port->data[1] = 0;
+		port->state = STATE_INITIAL;
 		if (b >= 0xc0 && b <= 0xdf)
-			port->state = STATE_1PARAM;
+			next_state = STATE_1PARAM;
 		else
-			port->state = STATE_2PARAM_1;
-	} else { /* b < 0x80 */
+			next_state = STATE_2PARAM_1;
+		break;
+
+	case 0x00 ... 0x7f:
+		/* Message parameters */
 		switch (port->state) {
 		case STATE_1PARAM:
-			if (port->data[0] < 0xf0) {
-				p0 |= port->data[0] >> 4;
-			} else {
-				p0 |= 0x02;
-				port->state = STATE_UNKNOWN;
-			}
-			f_midi_transmit_packet(req, p0, port->data[0], b, 0);
+			if (port->data[0] < 0xf0)
+				p[0] |= port->data[0] >> 4;
+			else
+				p[0] |= 0x02;
+
+			p[1] = port->data[0];
+			p[2] = b;
+			/* This is to allow Running State Messages */
+			next_state = STATE_1PARAM;
 			break;
 		case STATE_2PARAM_1:
 			port->data[1] = b;
-			port->state = STATE_2PARAM_2;
+			next_state = STATE_2PARAM_2;
 			break;
 		case STATE_2PARAM_2:
-			if (port->data[0] < 0xf0) {
-				p0 |= port->data[0] >> 4;
-				port->state = STATE_2PARAM_1;
-			} else {
-				p0 |= 0x03;
-				port->state = STATE_UNKNOWN;
-			}
-			f_midi_transmit_packet(req,
-				p0, port->data[0], port->data[1], b);
+			if (port->data[0] < 0xf0)
+				p[0] |= port->data[0] >> 4;
+			else
+				p[0] |= 0x03;
+
+			p[1] = port->data[0];
+			p[2] = port->data[1];
+			p[3] = b;
+			/* This is to allow Running State Messages */
+			next_state = STATE_2PARAM_1;
 			break;
 		case STATE_SYSEX_0:
 			port->data[0] = b;
-			port->state = STATE_SYSEX_1;
+			next_state = STATE_SYSEX_1;
 			break;
 		case STATE_SYSEX_1:
 			port->data[1] = b;
-			port->state = STATE_SYSEX_2;
+			next_state = STATE_SYSEX_2;
 			break;
 		case STATE_SYSEX_2:
-			f_midi_transmit_packet(req,
-				p0 | 0x04, port->data[0], port->data[1], b);
-			port->state = STATE_SYSEX_0;
+			p[0] |= 0x04;
+			p[1] = port->data[0];
+			p[2] = port->data[1];
+			p[3] = b;
+			next_state = STATE_SYSEX_0;
 			break;
 		}
+		break;
+	}
+
+	/* States where we have to write into the USB request */
+	if (next_state == STATE_FINISHED ||
+	    port->state == STATE_SYSEX_2 ||
+	    port->state == STATE_1PARAM ||
+	    port->state == STATE_2PARAM_2 ||
+	    port->state == STATE_REAL_TIME) {
+
+		unsigned int length = req->length;
+		u8 *buf = (u8 *)req->buf + length;
+
+		memcpy(buf, p, sizeof(p));
+		req->length = length + sizeof(p);
+
+		if (next_state == STATE_FINISHED) {
+			next_state = STATE_INITIAL;
+			port->data[0] = port->data[1] = 0;
+		}
 	}
+
+	port->state = next_state;
 }
 
 static void f_midi_drop_out_substreams(struct f_midi *midi)
@@ -641,7 +695,7 @@ static int f_midi_in_open(struct snd_rawmidi_substream *substream)
 	VDBG(midi, "%s()\n", __func__);
 	port = midi->in_ports_array + substream->number;
 	port->substream = substream;
-	port->state = STATE_UNKNOWN;
+	port->state = STATE_INITIAL;
 	return 0;
 }
 
-- 
2.9.2

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#1458231 — [PATCH v4 09/10] usb: gadget: f_hid: use free_ep_req()

We should always use free_ep_req() when allocating requests with
alloc_ep_req().

Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
---
 drivers/usb/gadget/function/f_hid.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/function/f_hid.c
index e82a7468252e..a010496e4e05 100644
--- a/drivers/usb/gadget/function/f_hid.c
+++ b/drivers/usb/gadget/function/f_hid.c
@@ -671,11 +671,8 @@ fail_free_descs:
 	usb_free_all_descriptors(f);
 fail:
 	ERROR(f->config->cdev, "hidg_bind FAILED\n");
-	if (hidg->req != NULL) {
-		kfree(hidg->req->buf);
-		if (hidg->in_ep != NULL)
-			usb_ep_free_request(hidg->in_ep, hidg->req);
-	}
+	if (hidg->req != NULL)
+		free_ep_req(hidg->in_ep, hidg->req);
 
 	return status;
 }
@@ -904,8 +901,7 @@ static void hidg_unbind(struct usb_configuration *c, struct usb_function *f)
 
 	/* disable/free request and end point */
 	usb_ep_disable(hidg->in_ep);
-	kfree(hidg->req->buf);
-	usb_ep_free_request(hidg->in_ep, hidg->req);
+	free_ep_req(hidg->in_ep, hidg->req);
 
 	usb_free_all_descriptors(f);
 }
-- 
2.9.2

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#1458232 — [PATCH v4 10/10] usb: gadget: f_hid: use alloc_ep_req()

Use gadget's framework allocation function instead of directly calling
usb_ep_alloc_request().

Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
---
 drivers/usb/gadget/function/f_hid.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/function/f_hid.c
index a010496e4e05..89d2e9a5a04f 100644
--- a/drivers/usb/gadget/function/f_hid.c
+++ b/drivers/usb/gadget/function/f_hid.c
@@ -611,14 +611,10 @@ static int hidg_bind(struct usb_configuration *c, struct usb_function *f)
 
 	/* preallocate request and buffer */
 	status = -ENOMEM;
-	hidg->req = usb_ep_alloc_request(hidg->in_ep, GFP_KERNEL);
+	hidg->req = alloc_ep_req(hidg->in_ep, hidg->report_length);
 	if (!hidg->req)
 		goto fail;
 
-	hidg->req->buf = kmalloc(hidg->report_length, GFP_KERNEL);
-	if (!hidg->req->buf)
-		goto fail;
-
 	/* set descriptor dynamic values */
 	hidg_interface_desc.bInterfaceSubClass = hidg->bInterfaceSubClass;
 	hidg_interface_desc.bInterfaceProtocol = hidg->bInterfaceProtocol;
-- 
2.9.2

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#1458234 — [PATCH v4 05/10] usb: gadget: f_midi: defaults buflen sizes to 512

512 is the value used by wMaxPacketSize, as specified by the USB Spec. This
makes sure this driver uses, by default, the most optimal value for IN and OUT
endpoint requests.

Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
---
 drivers/usb/gadget/function/f_midi.c | 2 +-
 drivers/usb/gadget/legacy/gmidi.c    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
index 39018dea7035..a7b50ac947f8 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -1122,7 +1122,7 @@ static struct usb_function_instance *f_midi_alloc_inst(void)
 	opts->func_inst.free_func_inst = f_midi_free_inst;
 	opts->index = SNDRV_DEFAULT_IDX1;
 	opts->id = SNDRV_DEFAULT_STR1;
-	opts->buflen = 256;
+	opts->buflen = 512;
 	opts->qlen = 32;
 	opts->in_ports = 1;
 	opts->out_ports = 1;
diff --git a/drivers/usb/gadget/legacy/gmidi.c b/drivers/usb/gadget/legacy/gmidi.c
index fc2ac150f5ff..0bf39c3ccdb1 100644
--- a/drivers/usb/gadget/legacy/gmidi.c
+++ b/drivers/usb/gadget/legacy/gmidi.c
@@ -47,7 +47,7 @@ static char *id = SNDRV_DEFAULT_STR1;
 module_param(id, charp, S_IRUGO);
 MODULE_PARM_DESC(id, "ID string for the USB MIDI Gadget adapter.");
 
-static unsigned int buflen = 256;
+static unsigned int buflen = 512;
 module_param(buflen, uint, S_IRUGO);
 MODULE_PARM_DESC(buflen, "MIDI buffer length");
 
-- 
2.9.2

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