2014-04-04 16:06 GMT+02:00 Stanislaw Gruszka <sgruszka@xxxxxxxxxx>: > On Fri, Apr 04, 2014 at 11:01:06AM +0200, Jakub Kiciński wrote: >> On Fri, 4 Apr 2014 10:19:09 +0200, Stanislaw Gruszka wrote: >> > On Thu, Apr 03, 2014 at 05:37:01PM +0200, Jakub Kiciński wrote: >> > > On Thu, 3 Apr 2014 16:12:07 +0200, Richard Genoud wrote: >> > > > rt2x00usb_register_read_lock() calls rt2x00usb_vendor_req_buff_lock() >> > > > that calls rt2x00usb_vendor_request() which is already looping up to >> > > > REGISTER_BUSY_COUNT times. >> > > > >> > > > So this loop is not needed. >> > > >> > > Not true. rt2x00usb_vendor_request() busy-waits for usb_control_msg() >> > > to succeed, rt2x00usb_register_read_lock() busy-waits for the register >> > > field itself to become 0. >> > >> > Yeah, but still we are looping REGISTER_BUSY_COUNT*REGISTER_BUSY_COUNT >> > what seems to be far too long. >> >> Yes, the busy waiting itself takes roughly 1s (100*100*100us) and then >> there are transfer times, so it might be too long indeed. Vendor driver >> waits only 10 * 5ms in RTUSB_VendorRequest() so > > We use "timeout" argument which is set to 500ms , so perhaps that > could be the reason why Richard sees "infinite" loop i.e. > 100*100*(500ms + 100us) That's what I thougth at the begining, so I applied this patch, but it was still looping on errors -EPROTO. >> rt2x00usb_vendor_request() seems like a better place to cut down the >> number of loops. >> >> Alternatively we could make rt2x00usb_regbusy_read() check the retval >> from rt2x00usb_vendor_request() and exit early? > > Make sense, but I think we should review the area and make some more > changes to fine tune the timeout of USB reg reading functions. > > Stanislaw -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
