linux-kernel - [PATCH v3 3/4] usb: gadget: f_midi: Transmit data only when IN ep is enabled

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Date:	Tue, 29 Sep 2015 13:01:58 +0100
From:	"Felipe F. Tonello" <eu@...ipetonello.com>
To:	linux-usb@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org,
	Peter Chen <Peter.Chen@...escale.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Felipe Balbi <balbi@...com>,
	Andrzej Pietrasiewicz <andrzej.p@...sung.com>,
	"Felipe F. Tonello" <eu@...ipetonello.com>
Subject: [PATCH v3 3/4] usb: gadget: f_midi: Transmit data only when IN ep is enabled

This makes sure f_midi doesn't try to enqueue data when the IN endpoint is
disabled, ie, USB cable is disconnected.

Signed-off-by: Felipe F. Tonello <eu@...ipetonello.com>
---
 drivers/usb/gadget/function/f_midi.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
index 163c0ce..bbfe43b 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -87,6 +87,7 @@ struct f_midi {
 	int index;
 	char *id;
 	unsigned int buflen, qlen;
+	bool in_ep_enabled;
 };
 
 static inline struct f_midi *func_to_midi(struct usb_function *f)
@@ -331,6 +332,7 @@ static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 	err = f_midi_start_ep(midi, f, midi->in_ep);
 	if (err)
 		return err;
+	midi->in_ep_enabled = true;
 
 	err = f_midi_start_ep(midi, f, midi->out_ep);
 	if (err)
@@ -386,6 +388,8 @@ static void f_midi_disable(struct usb_function *f)
 	 */
 	usb_ep_disable(midi->in_ep);
 	usb_ep_disable(midi->out_ep);
+
+	midi->in_ep_enabled = false;
 }
 
 static int f_midi_snd_free(struct snd_device *device)
@@ -542,7 +546,7 @@ static void f_midi_transmit(struct f_midi *midi, struct usb_request *req)
 		}
 	}
 
-	if (req->length > 0) {
+	if (req->length > 0 && midi->in_ep_enabled) {
 		int err;
 
 		err = usb_ep_queue(ep, req, GFP_ATOMIC);
@@ -1159,6 +1163,7 @@ 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_ep_enabled = false;
 	++opts->refcnt;
 	mutex_unlock(&opts->lock);
 
-- 
2.1.4

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