On Tue, Jun 14, 2011 at 6:28 PM, Felipe Balbi <balbi@xxxxxx> wrote: > On Tue, Jun 14, 2011 at 12:25:11PM +0200, Mikael Abrahamsson wrote: >> (taking it offlist just because I have no idea about anything really) > > c'mon, quite good point below ;-) > >> >yeah, but if the problem isn't throughput, I don't see how MUSB >> >could be to blame here. The network priority should have been >> >handled by IP layer and the controller shouldn't matter, right ? >> >> I'm just a silly router guy, but I've seen on router platforms that >> when the device driver has a big buffer (FIFO) that the IP layer >> feeds into (which then does some kind of priority scheduling of >> packets), one loses a lot of QoS capabilities. > > MUSB doesn't have any big buffers of its own. In this situation it's > using the buffers from usbcore. So it should be the same on the ISP1362 > host ;-) > > Good point anyway :-D > >> So the device driver can indeed cause these kinds of problems, if it >> doesn't push back the congestion to the IP layer properly. Also if >> the device FIFO buffer drops packets on its own the same behaviour >> can be seen. > > USB won't drop packets unless you explicitly tell it to flush the HW > FIFOs. I don't think this is the case here either. > Actually I saw this happen because wireless driver called usb_unlink_urb(). i don't know what's ISP1362 did in this situation, but it seems musb will flush the HW FIFOs. Maybe this will cause the priority problem ? I am not sure :-). -- Regards, --Bob -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
