Dear Oliver forgive me for my many questions but here are the
modificaions that u adviced me to do but i think there is still
something wrong because when the gadget sends "hello" for example to
the host, my computer is hanging so what is the error ,i m gonna be
made:
here is the last code for skel_read:
static void skel_read_bulk_callback(struct urb *urb, struct pt_regs *regs)
{
struct usb_skel *dev;
complete((struct completion *)urb->context);
dev = (struct usb_skel *)urb->context;
up(&dev->limit_sem);
}
static ssize_t skel_read(struct file *file, char *user_buffer, size_t
count, loff_t *ppos)
{
struct completion done;
struct usb_skel *dev;
int retval = 0;
struct urb *urb = NULL;
char *buf = NULL;
size_t readsize = min(count, (size_t)MAX_TRANSFER);
dev = (struct usb_skel *)file->private_data;
/* verify that we actually have some data to read */
if (count == 0)
goto exit;
/* limit the number of URBs in flight to stop a user from using up all
RAM */
if (down_interruptible(&dev->limit_sem)) {
retval = -ERESTARTSYS;
goto exit;
}
init_completion(&done);
/* create a urb, and a buffer for it, and copy the data to the urb */
urb = usb_alloc_urb(0, GFP_KERNEL);
if (!urb) {
retval = -ENOMEM;
goto error;
}
buf = usb_buffer_alloc(dev->udev, readsize, GFP_KERNEL,
&urb->transfer_dma);
if (!buf) {
retval = -ENOMEM;
goto error;
}
/* initialize the urb properly */
usb_fill_bulk_urb(urb, dev->udev,
usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
buf, readsize, skel_read_bulk_callback, &done);
urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
/* send the data out the bulk port */
retval = usb_submit_urb(urb, GFP_KERNEL);
if (retval) {
err("%s - failed submitting read urb, error %d", __FUNCTION__,
retval);
goto error;
}
wait_for_completion(&done);
if ( copy_to_user(user_buffer, dev->bulk_in_buffer,
urb->actual_length) )
retval = -EFAULT;
else
retval = urb->actual_length;
/* free up our allocated buffer */
usb_buffer_free(urb->dev, urb->transfer_buffer_length,
urb->transfer_buffer, urb->transfer_dma);
/* release our reference to this urb, the USB core will eventually
free it entirely */
usb_free_urb(urb);
return retval;
exit:
return retval;
error:
usb_buffer_free(dev->udev, readsize, buf, urb->transfer_dma);
usb_free_urb(urb);
up(&dev->limit_sem);
return retval;
}
thanks in advance
yours nesta
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