Docs: usb: update writesize, copy_from_user, usb_fill_bulk_urb, usb_submit_urb

update code examples writesize, copy_from_user, usb_fill_bulk_urb,
usb_submit_urb in skel_write() according to usb-skeleton.c

Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/0c581a83dfc1a8c37e97dfa7279d333f367a9787.1635591623.git.philipp.g.hortmann@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/driver-api/usb/writing_usb_driver.rst b/Documentation/driver-api/usb/writing_usb_driver.rst
index a6b11bf..95c4f5d 100644 (file)
--- a/Documentation/driver-api/usb/writing_usb_driver.rst
+++ b/Documentation/driver-api/usb/writing_usb_driver.rst
@@ -188,24 +188,26 @@ space, points the urb to the data and submits the urb to the USB
 subsystem. This can be seen in the following code::
 
     /* we can only write as much as 1 urb will hold */
-    bytes_written = (count > skel->bulk_out_size) ? skel->bulk_out_size : count;
+    size_t writesize = min_t(size_t, count, MAX_TRANSFER);
 
     /* copy the data from user space into our urb */
-    copy_from_user(skel->write_urb->transfer_buffer, buffer, bytes_written);
+    copy_from_user(buf, user_buffer, writesize);
 
     /* set up our urb */
-    usb_fill_bulk_urb(skel->write_urb,
-                     skel->dev,
-                     usb_sndbulkpipe(skel->dev, skel->bulk_out_endpointAddr),
-                     skel->write_urb->transfer_buffer,
-                     bytes_written,
+    usb_fill_bulk_urb(urb,
+                     dev->udev,
+                     usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
+                     buf,
+                     writesize,
                      skel_write_bulk_callback,
-                     skel);
+                     dev);
 
     /* send the data out the bulk port */
-    result = usb_submit_urb(skel->write_urb);
-    if (result) {
-           err("Failed submitting write urb, error %d", result);
+    retval = usb_submit_urb(urb, GFP_KERNEL);
+    if (retval) {
+           dev_err(&dev->interface->dev,
+                "%s - failed submitting write urb, error %d\n",
+                __func__, retval);
     }