On Fri, 24 Jul 2009, Madhavi Manchala wrote:
> Dear Alan,
>
> The below snippet is used to allocate the buffer heads. Currently
> NUM_BUFFERS is defined to 2. I would like to change it 4. Two buffer
> heads per thread. Is this the correct approach?
Look again. This code doesn't allocate buffer heads; it allocates
usb_request structures. See the comment and the calls to
alloc_request()?
> /* Allocate the requests */
> for (i = 0; i < NUM_BUFFERS; ++i) {
> struct fsg_buffhd *bh = &fsg->buffhds[i];
>
> if ((rc = alloc_request(fsg, fsg->bulk_in, &bh->inreq)) != 0)
> goto reset;
> if ((rc = alloc_request(fsg, fsg->bulk_out, &bh->outreq)) != 0)
> goto reset;
> bh->inreq->buf = bh->outreq->buf = bh->buf;
> bh->inreq->context = bh->outreq->context = bh;
> bh->inreq->complete = bulk_in_complete;
> bh->outreq->complete = bulk_out_complete;
> }
>
> Does dummy hcd understand the changes and use the FOUR buffers heads
> instead of TWO buffer heads?
dummy-hcd doesn't use buffer heads at all; it uses only usb_requests.
There's a reason why the structures are named "fsg_buffhd" -- it's
because they are private to the fsg driver.
Alan Stern
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