Hi, Bin Liu <b-liu@xxxxxx> writes: > I am relatively new to xhci and its driver. I am trying to get a xhci > driver runtime log to understand how it handles usb transactions, but I > don't get much information with dynamic debug (module xhci_hcd) or > enabling xhci trace events. Is there any other methods you guys use to > debug xhci driver? tracepoints, the best thing since sliced bread ;-) > BTY, the issue I am trying to debug is when reading bulk IN data from a > USB2.0 device, if the device doesn't have data to transmit and NAKs the > IN packet, after 4 pairs of IN-NAK transactions, xhci stops sending > further IN tokens until the next SOF, which leaves ~90us gape on the > bus. > > But when reading data from a USB2.0 thumb drive, this issue doesn't > happen, even if the device NAKs the IN tokens, xhci still keeps sending > IN tokens, which is way more than 4 pairs of IN-NAK transactions. Thumb drive has Bulk endpoints, what is the other device's transfer type? > Any one has a clue on what causes xhci to stop sending IN tokens after > the device NAK'd 4 times? tracepoints, please :-) -- 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
