USB: autosuspend for usblcd

this patch implements autosuspend for the usblcd driver. It uses
the new usb_anchor infrastructure. Many thanks to Georges for testing.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Cc: Georges Toth <g.toth@e-biz.lu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 43 insertions, 3 deletions

diff --git a/drivers/usb/misc/usblcd.c b/drivers/usb/misc/usblcd.c
index 6e093c2aac2c..504f7221b0d0 100644
--- a/drivers/usb/misc/usblcd.c
+++ b/drivers/usb/misc/usblcd.c
@@ -45,6 +45,7 @@ struct usb_lcd {
         struct kref             kref;
         struct semaphore        limit_sem;              /* to stop writes at full throttle from
                                                          * using up all RAM */
+        struct usb_anchor       submitted;              /* URBs to wait for before suspend */
 };
 #define to_lcd_dev(d) container_of(d, struct usb_lcd, kref)
 
@@ -67,7 +68,7 @@ static int lcd_open(struct inode *inode, struct file *file)
 {
         struct usb_lcd *dev;
         struct usb_interface *interface;
-        int subminor;
+        int subminor, r;
 
         subminor = iminor(inode);
 
@@ -85,6 +86,13 @@ static int lcd_open(struct inode *inode, struct file *file)
         /* increment our usage count for the device */
         kref_get(&dev->kref);
 
+        /* grab a power reference */
+        r = usb_autopm_get_interface(interface);
+        if (r < 0) {
+                kref_put(&dev->kref, lcd_delete);
+                return r;
+        }
+
         /* save our object in the file's private structure */
         file->private_data = dev;
 
@@ -100,6 +108,7 @@ static int lcd_release(struct inode *inode, struct file *file)
                 return -ENODEV;
 
         /* decrement the count on our device */
+        usb_autopm_put_interface(dev->interface);
         kref_put(&dev->kref, lcd_delete);
         return 0;
 }
@@ -225,12 +234,14 @@ static ssize_t lcd_write(struct file *file, const char __user * user_buffer, siz
                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
                           buf, count, lcd_write_bulk_callback, dev);
         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+
+        usb_anchor_urb(urb, &dev->submitted);
         
         /* send the data out the bulk port */
         retval = usb_submit_urb(urb, GFP_KERNEL);
         if (retval) {
                 err("USBLCD: %s - failed submitting write urb, error %d", __FUNCTION__, retval);
-                goto error;
+                goto error_unanchor;
         }
         
         /* release our reference to this urb, the USB core will eventually free it entirely */
@@ -238,7 +249,8 @@ static ssize_t lcd_write(struct file *file, const char __user * user_buffer, siz
 
 exit:
         return count;
-
+error_unanchor:
+        usb_unanchor_urb(urb);
 error:
         usb_buffer_free(dev->udev, count, buf, urb->transfer_dma);
         usb_free_urb(urb);
@@ -283,6 +295,7 @@ static int lcd_probe(struct usb_interface *interface, const struct usb_device_id
         }
         kref_init(&dev->kref);
         sema_init(&dev->limit_sem, USB_LCD_CONCURRENT_WRITES);
+        init_usb_anchor(&dev->submitted);
 
         dev->udev = usb_get_dev(interface_to_usbdev(interface));
         dev->interface = interface;
@@ -350,6 +363,30 @@ error:
         return retval;
 }
 
+static void lcd_draw_down(struct usb_lcd *dev)
+{
+        int time;
+
+        time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
+        if (!time)
+                usb_kill_anchored_urbs(&dev->submitted);
+}
+
+static int lcd_suspend(struct usb_interface *intf, pm_message_t message)
+{
+        struct usb_lcd *dev = usb_get_intfdata(intf);
+
+        if (!dev)
+                return 0;
+        lcd_draw_down(dev);
+        return 0;
+}
+
+static int lcd_resume (struct usb_interface *intf)
+{
+        return 0;
+}
+
 static void lcd_disconnect(struct usb_interface *interface)
 {
         struct usb_lcd *dev;
@@ -371,7 +408,10 @@ static struct usb_driver lcd_driver = {
         .name =         "usblcd",
         .probe =        lcd_probe,
         .disconnect =   lcd_disconnect,
+        .suspend =      lcd_suspend,
+        .resume =       lcd_resume,
         .id_table =     id_table,
+        .supports_autosuspend = 1,
 };
 
 static int __init usb_lcd_init(void)