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Commit 73e06865 authored by Greg Suarez's avatar Greg Suarez Committed by Greg Kroah-Hartman
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USB: cdc-wdm: support back-to-back USB_CDC_NOTIFY_RESPONSE_AVAILABLE notifications 



Some MBIM devices send back-to-back USB_CDC_NOTIFY_RESPONSE_AVAILABLE notifications
when sending a message over multiple fragments or when there are unsolicited
messages available.

Count up the number of USB_CDC_NOTIFY_RESPONSE_AVAILABLE notifications received
and decrement the count and submit the urb for the next response each time userspace
completes a read the response.

Signed-off-by: default avatarGreg Suarez <gsuarez@smithmicro.com>
Acked-by: default avatarBjørn Mork <bjorn@mork.no>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 32e24930

drivers/usb/class/cdc-wdm.c

+34 −4
Original line number Diff line number Diff line
@@ -101,6 +101,7 @@ struct wdm_device { 
	struct work_struct	rxwork;

	int			werr;

	int			rerr;

	int                     resp_count;



	struct list_head	device_list;

	int			(*manage_power)(struct usb_interface *, int);
@@ -262,9 +263,9 @@ static void wdm_int_callback(struct urb *urb) 
	}



	spin_lock(&desc->iuspin);

	clear_bit(WDM_READ, &desc->flags);

	responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);

	if (!responding && !test_bit(WDM_DISCONNECTING, &desc->flags)

	if (!desc->resp_count++ && !responding

		&& !test_bit(WDM_DISCONNECTING, &desc->flags)

		&& !test_bit(WDM_SUSPENDING, &desc->flags)) {

		rv = usb_submit_urb(desc->response, GFP_ATOMIC);

		dev_dbg(&desc->intf->dev, "%s: usb_submit_urb %d",
@@ -521,9 +522,35 @@ static ssize_t wdm_read 


	desc->length -= cntr;

	/* in case we had outstanding data */

	if (!desc->length)

	if (!desc->length) {

		clear_bit(WDM_READ, &desc->flags);



		if (--desc->resp_count) {

			set_bit(WDM_RESPONDING, &desc->flags);

			spin_unlock_irq(&desc->iuspin);



			rv = usb_submit_urb(desc->response, GFP_KERNEL);

			if (rv) {

				dev_err(&desc->intf->dev,

					"%s: usb_submit_urb failed with result %d\n",

					__func__, rv);

				spin_lock_irq(&desc->iuspin);

				clear_bit(WDM_RESPONDING, &desc->flags);

				spin_unlock_irq(&desc->iuspin);



				if (rv == -ENOMEM) {

					rv = schedule_work(&desc->rxwork);

					if (rv)

						dev_err(&desc->intf->dev, "Cannot schedule work\n");

				} else {

					spin_lock_irq(&desc->iuspin);

					desc->resp_count = 0;

					spin_unlock_irq(&desc->iuspin);

				}

			}

		} else

			spin_unlock_irq(&desc->iuspin);

	} else

		spin_unlock_irq(&desc->iuspin);



	rv = cntr;
@@ -635,6 +662,9 @@ static int wdm_release(struct inode *inode, struct file *file) 
		if (!test_bit(WDM_DISCONNECTING, &desc->flags)) {

			dev_dbg(&desc->intf->dev, "wdm_release: cleanup");

			kill_urbs(desc);

			spin_lock_irq(&desc->iuspin);

			desc->resp_count = 0;

			spin_unlock_irq(&desc->iuspin);

			desc->manage_power(desc->intf, 0);

		} else {

			/* must avoid dev_printk here as desc->intf is invalid */