[PATCH]autosuspend for cdc-acm

Hi,

this patch implements autosuspend for CDC ACM devices. It addresses
Alan's concerns about using the existing suspend/resume methods for
this. Locking indeed has been had to be changed.

	Regards
		Oliver

Signed-off-by: Oliver Neukum <[email protected]>

----

--- linux-2.6.23-rc9/drivers/usb/class/cdc-acm.h	2007-10-11 10:02:26.000000000 +0200
+++ acm/drivers/usb/class/cdc-acm.h	2007-10-10 12:55:12.000000000 +0200
@@ -107,6 +107,7 @@ struct acm {
 	int write_used;					/* number of non-empty write buffers */
 	int write_ready;				/* write urb is not running */
 	spinlock_t write_lock;
+	struct mutex mutex;
 	struct usb_cdc_line_coding line;		/* bits, stop, parity */
 	struct work_struct work;			/* work queue entry for line discipline waking up */
 	struct tasklet_struct urb_task;                 /* rx processing */
--- linux-2.6.23-rc9/drivers/usb/class/cdc-acm.c	2007-10-11 10:02:26.000000000 +0200
+++ acm/drivers/usb/class/cdc-acm.c	2007-10-11 09:38:08.000000000 +0200
@@ -496,10 +496,19 @@ static int acm_tty_open(struct tty_struc
 	   otherwise it is scheduled, and with high data rates data can get lost. */
 	tty->low_latency = 1;
 
+	if (usb_autopm_get_interface(acm->control)) {
+		mutex_unlock(&open_mutex);
+		return -EIO;
+	}
+
+	mutex_lock(&acm->mutex);
+	mutex_unlock(&open_mutex);
 	if (acm->used++) {
+		usb_autopm_put_interface(acm->control);
 		goto done;
         }
 
+
 	acm->ctrlurb->dev = acm->dev;
 	if (usb_submit_urb(acm->ctrlurb, GFP_KERNEL)) {
 		dbg("usb_submit_urb(ctrl irq) failed");
@@ -526,14 +535,15 @@ static int acm_tty_open(struct tty_struc
 
 done:
 err_out:
-	mutex_unlock(&open_mutex);
+	mutex_unlock(&acm->mutex);
 	return rv;
 
 full_bailout:
 	usb_kill_urb(acm->ctrlurb);
 bail_out:
+	usb_autopm_put_interface(acm->control);
 	acm->used--;
-	mutex_unlock(&open_mutex);
+	mutex_unlock(&acm->mutex);
 	return -EIO;
 }
 
@@ -570,6 +580,7 @@ static void acm_tty_close(struct tty_str
 			usb_kill_urb(acm->writeurb);
 			for (i = 0; i < nr; i++)
 				usb_kill_urb(acm->ru[i].urb);
+			usb_autopm_put_interface(acm->control);
 		} else
 			acm_tty_unregister(acm);
 	}
@@ -980,6 +991,7 @@ skip_normal_probe:
 	spin_lock_init(&acm->throttle_lock);
 	spin_lock_init(&acm->write_lock);
 	spin_lock_init(&acm->read_lock);
+	mutex_init(&acm->mutex);
 	acm->write_ready = 1;
 	acm->rx_endpoint = usb_rcvbulkpipe(usb_dev, epread->bEndpointAddress);
 
@@ -1112,7 +1124,7 @@ static void stop_data_traffic(struct acm
 
 	tasklet_enable(&acm->urb_task);
 
-	flush_scheduled_work(); /* wait for acm_softint */
+	cancel_work_sync(&acm->work);
 }
 
 static void acm_disconnect(struct usb_interface *intf)
@@ -1170,15 +1182,15 @@ static int acm_suspend(struct usb_interf
 	if (acm->susp_count++)
 		return 0;
 	/*
-	we treat opened interface differently,
-	we must giard against open
+	we treat opened interfaces differently,
+	we must guard against open 
 	*/
-	mutex_lock(&open_mutex);
+	mutex_lock(&acm->mutex);
 
 	if (acm->used)
 		stop_data_traffic(acm);
 
-	mutex_unlock(&open_mutex);
+	mutex_unlock(&acm->mutex);
 	return 0;
 }
 
@@ -1190,7 +1202,7 @@ static int acm_resume(struct usb_interfa
 	if (--acm->susp_count)
 		return 0;
 
-	mutex_lock(&open_mutex);
+	mutex_lock(&acm->mutex);
 	if (acm->used) {
 		rv = usb_submit_urb(acm->ctrlurb, GFP_NOIO);
 		if (rv < 0)
@@ -1200,7 +1212,7 @@ static int acm_resume(struct usb_interfa
 	}
 
 err_out:
-	mutex_unlock(&open_mutex);
+	mutex_unlock(&acm->mutex);
 	return rv;
 }
 /*
@@ -1258,6 +1270,7 @@ static struct usb_driver acm_driver = {
 	.suspend =	acm_suspend,
 	.resume =	acm_resume,
 	.id_table =	acm_ids,
+	.supports_autosuspend = 1,
 };
 
 /*

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