Hi,
linux-usb-devel is the better place for these types of questions, but
I'll give it a go...
On Thu, Dec 20, 2001 at 10:18:08PM -0800, Angderson, Charyll wrote:
> i expect that the bulk data read on the wire would be the same data in
> "buf". i see different data on the wire than that returned by "buf" 50% of
> the time.
>
> isoc reads seem to be consistent. and both isoc/bulk writes are correct. i
> only have one "buf". i've tried making "buf" a static pointer: static WORD
> * buf;
What's a "WORD" size? Any reason you aren't using "unsigned char"?
> and when ever user wants to do transfers i have to read the "size"
> they pass in and do a "kmalloc" for "buf". after each transaction "buf" is
> freed. but definitely not until transaction is done.
>
> i even have a print statement right after transaction completes (see below)
> and it proves that "buf" is bad.
>
> anyone have any ideas? snippet of my code is below.
>
> thanks,
> -charyll angderson
>
> int usbx_submit_trans(struct usbxDevice *usbxPtr, struct usb_device *dev,
> struct _Transaction *trans, WORD *buf)
> {
> int i,j,k;
> usbx_show_trans(trans);
>
> switch(trans->type) {
> case USBX_R_BULK:
> FILL_BULK_URB(usbxPtr->usbx_urb, dev, usb_rcvbulkpipe(dev,
> trans->endpoint),
> buf, trans->size, usbx_urb_complete, usbxPtr);
> break;
> default:
> dbg("invaid trans type!");
> break;
> }
>
> usbx_submit_urb(usbxPtr->usbx_urb);
> interruptible_sleep_on_timeout(&(usbxPtr->wait), trans->timeout);
Does your callback wake up your "wait"?
> if (usbxPtr->usbx_urb->status!=0) {
> err("TIMEOUT awoken %i (%s)
> status=0x%x",current->pid,current->comm,usbxPtr->usbx_urb->status); //ca
> debug
> usbx_unlink_urb(usbxPtr->usbx_urb); // remove urb safely
I recommend unlinking in your callback, much easier.
> }
>
> switch (trans->type) {
> case USBX_R_BULK:
> dbg("usbx_submit_trans: print buffer read ..
> address=0x%lx", (DWORD)&buf);
> for (i=0; i<(trans->size/2); i++) {
> dbg(" %x ",(WORD)buf[i]);
You should use the urb->actual_length field here. That tells you how
many bytes you received (which can be different from what you
requested). Also, what's with the "size/2" stuff? We are transferring
bytes here :)
If you want to do a bulk read that blocks until completed (or timed
out) there already is a usb core function that does it called
usb_bulk_msg() keeping you from having to roll your own.
Hope this helps,
greg k-h
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