Hi, Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> writes: > Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> writes: >> On Mon, 16 Jan 2017, Felipe Balbi wrote: >> >>> Sorry for the long delay, I finally have more information on this. All >>> this time I was doing something that I never considered to matter: I've >>> been running host and peripheral on the same machine. Now that I have >>> tracepoints on xHCI as well, I could see that these 30 seconds of >>> "nothing" is actuall full of xHCI activity and I can see that for the >>> duration of these 30 seconds preempt depth on the CPU that (eventually) >>> queues a request on dwc3, is always > 1 (sometimes 2, most of the time >>> 1). My conclusion from that is that xHCI (or usbcore ?!?) locks the CPU >>> and g_mass_storage is spinning for over 30 seconds at which point >>> storage.ko (host side class driver) dequeues the request. >>> >>> I'll see if I can capture a fresh trace with both xHCI and dwc3 with >>> this happening, but probably not today (testing stuff for -rc). >> >> Does anything change if the host and peripheral are separate machines? > > couldn't reproduce the problem yet ;-) *yet* is a keyword here. I wouldn't call this problem "done" until I successfully run my test case for at least a week. -- balbi -- 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
