On Mon, Jun 11, 2007 at 12:50:20PM -0400, Alan Stern wrote: > On Mon, 11 Jun 2007, Greg KH wrote: > > > > Another idea suggested itself too: We could make usbcore allocate > > > urb->hcpriv during submission instead of having each HCD do its own > > > private allocation. It's not a big deal, just a matter of replacing > > > several different calls to kmalloc/kfree by a single call. Any reason > > > not to do it? > > > > No objection from me. > > It turns out to be harder than I thought it would. ohci-hcd allocates > a variable-length private structure, depending on the transfer length. > This means we can't simply store an urb_hcpriv_size field in the > hc_driver structure. So I'm not going to do this now; it can be added > later.
Ok. I would like to bind a buffer to an urb "easier" than we have today (the two-stage thing is a bit odd compared to other interfaces in the kernel. We almost always know the size of the buffer we are going to assign the urb when we create it anyway...) But that can happen later. > > > Ideally, of course, each HCD would allocate its own URBs with the > > > private area included. But we can't do that just now, since some > > > drivers maintain pools of URBs that they use for multiple devices, > > > potentially on different buses. > > > > I don't object to fixing those drivers to do a per-device pool instead > > of a per-driver pool to make this easier. > > > > So then you could just do a: > > usb_alloc_urb(struct usb_interface *intf, ...) > > which would allow the bus that is assigned to the device to do the > > proper allocation? I think that would be good to do. > > That can be the second major alteration -- first get rid of > urb->status, then change URB allocation. Large changes like this take > some time... Ok, sounds reasonable. thanks, greg k-h ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
