Hi, On Mon, Oct 16, 2017 at 1:49 PM, Julius Werner <jwerner@xxxxxxxxxxxx> wrote: >> d9a14b00 339317035 C Ii:1:004:1 -32:1 0 >> d9a14b00 339317049 S Ii:1:004:1 -115:1 10 < >> d9a14b00 339318040 C Ii:1:004:1 -32:1 0 >> d9a14b00 339318057 S Ii:1:004:1 -115:1 10 < >> d9a14b00 339319042 C Ii:1:004:1 -32:1 0 >> d9a14b00 339319056 S Ii:1:004:1 -115:1 10 < >> d9a14b00 339329551 C Ii:1:004:1 -32:1 0 >> d9a14b00 339329571 S Ii:1:004:1 -115:1 10 < >> d9a14b00 339330586 C Ii:1:004:1 -32:1 0 >> d9a14b00 339330601 S Ii:1:004:1 -115:1 10 < >> d9a14b00 339331035 C Ii:1:004:1 -32:1 0 > > Sorry for necromancing an old thread, but I just happened to read > through this and thought someone might care: > > If I read that right, the usbmon output shows that the interrupt > endpoint is stalled (keeps returning -EPIPE). A STALL is a special > device-side USB condition that tells the host something is wrong and > will persist until cleared manually. It seems that the driver isn't > prepared for this (see > drivers/usb/serial/pl2303.c#pl2303_read_int_callback) and just keeps > resubmitting the URB, so it will stall again as fast as the endpoint > allows it to. This may be the reason why you get so many transfers > that it overwhelms the CPU. > > A fix would be to catch -EPIPE in that function and handle it > explicitly (with either a CLEAR_STALL to the endpoint or a full USB > reset... would have to look at the documentation for PL2303 to see > what the stall actually means and how you're supposed to treat it). To further comment on this old thread, I just posted another patch at <https://patchwork.kernel.org/patch/10027237/> that could also make pl2303 less able to bring dwc2-based controllers to a screeching halt. I added many of the people who had taken part in this thread, but if you were just lurking here then hopefully you can dig it up and try it out. -Doug -- 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
