On Fri, 6 Sep 2013, Oleksij Rempel wrote: > Hi Alan, > > i need more help. > > We have more test results now. Initial patch was probably fixing > fallowing issue - bad performance on EP4/EP3 if Intr transfer is used. > It is reproducible only on EHCI, but not reproducible on xHCI controller. Is this a high-speed device? What version of the kernel are you using? > For example, channel scan function intensively use this endpoints. On > xHCI, channel scan is done in 6 seconds. On EHCI it needs 25s. By > forcing Bulk transfer on host side, it is possible get same performance > on EHCI too. But it isn't working on all controllers because of limited > packed size (64B). > > Dumps are attached. One of them may include some other device, but only > ath9k_htc device has EP3 and EP4. The capture logs show that with EHCI, each endpoint transfers a packet every 2.5 ms or so, whereas xHCI transfers 2-3 packets per ms. > Is it protocol limitation or HC issue? It's not a protocol limitation. If it were, the xHCI communication would be just as slow as EHCI. One thing that might help: For each endpoint, keep multiple URBs queued (try 10) at all times instead of just a single URB. It's entirely possible that these results are caused by limitations of your EHCI hardware. Still, using multiple URBs could yield a significant improvement. Alan Stern -- 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
