hi all,
i have 2 questions:
1) i make simple while loop,at the host side, in which i m receiving the data
using the read function of usb-skeleton module,it is as follows:
***************************************************************************
do
{
insize =read (fd,(char*)inbuff, sizeof (inbuff) );
printf("insize is %d\n",insize);
printf(" %s\n",inbuff);
}while (strcmp(inbuff,"end"));
****************************************************************************
my aim is : when the gadget has something to send to the host this while loop
will print what the hosts receives from the gadget.
but this does not happen when i use the skel_read function,it is in
usb-skeleton.c,as when the gadget does not have anything to send to the host,i
found that the read function is non-blocking and it prints the following
forever:
insize is -1
black line //i think this is because inbuff is empty
anyway i found that there is a function in skel_read function, named by
usb_bulk_msg and the last argument of it, is the timeout and if i set this
timeout to zero it will stop printing insize is -1 and thus it becomes a
blocking function.
so now if the gadget is not sending anything to the host, the while loop stops
printing
insize is -1
bu when the gadget really sends a word like "hello host" for example, the host
really receives it but still printing the phrase of insize is 64 i.e the output
is as follows:
insize is 64
hello host
insize is 64
insize is 64 and it prints this phrase forever
so why it just receives 64B while i was really sending 2KB buffer?
actually what i want exactly is when the gadget sends "hello host" the while
looop output is :
insize is 2048 // 2KB=2048
hello host
and doesnt print anything else?
2) can i make the following steps in reading instead of usb_bulk_msg:
1.urb = usb_alloc_urb(0, GFP_KERNEL);
2.buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
3.copy_to_user(buf, user_buffer, readsize
4.usb_fill_bulk_urb( urb, dev->udev,
usb_rcvctrlpipe(dev->udev, dev->bulk_in_endpointAddr),
buf, readsize, skel_read_bulk_callback, dev);
5.urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
6.usb_submit_urb
the location of copy_to_user is correct?or it should be put after
usb_submit_urb?
this is the same algorithm for skel_write.so can i make the same algorithm with
skel_read?or not?
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