On Wed, 11 Sep 2013, Oleksij Rempel wrote: > >> Same issue on two different intel controllers. I'll try some thing > >> different for comparison. > > > > Don't try different hardware. Try submitting multiple URBs. > > Suddenly i can't submit multiple urbs, we have lots of read->write > operations. I need read result before i can write. Or do you mean some > thing different. Beside, all EPs except EP4 are configured for multiple > urbs. And ep4 is the one causing your problem... > Currently i was able to narrow down this problem. Only EP4 OUT is > affected, it takes 2.5 msec to get ACK from it. In the USB-3 scan file you sent, it takes less than 0.25 ms for URBs to ep4 to complete. I thought this might be caused by a difference between the host controllers, but maybe there's another reason. Maybe the device is the cause. > Then i found one interesting register. It switch between packet and > stream mode for OUT endpoints. Suddenly it will affect all EP* OUT. > Enabling packet mode will solve this problem for EP4, but introduce some > other DMA related problem on EP1... :( If you're not using ep1 and ep4 at the same time, it won't matter. > Do this modes are USB protocol related? I was not able to find some > thing to read about it, or may be i just search for wrong words. I don't know anything about packet or stream modes for your device. I have never heard of them before. 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
