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1===========2DWC3 driver3===========4 5 6TODO7~~~~8 9Please pick something while reading :)10 11- Convert interrupt handler to per-ep-thread-irq12 13 As it turns out some DWC3-commands ~1ms to complete. Currently we spin14 until the command completes which is bad.15 16 Implementation idea:17 18 - dwc core implements a demultiplexing irq chip for interrupts per19 endpoint. The interrupt numbers are allocated during probe and belong20 to the device. If MSI provides per-endpoint interrupt this dummy21 interrupt chip can be replaced with "real" interrupts.22 - interrupts are requested / allocated on usb_ep_enable() and removed on23 usb_ep_disable(). Worst case are 32 interrupts, the lower limit is two24 for ep0/1.25 - dwc3_send_gadget_ep_cmd() will sleep in wait_for_completion_timeout()26 until the command completes.27 - the interrupt handler is split into the following pieces:28 29 - primary handler of the device30 goes through every event and calls generic_handle_irq() for event31 it. On return from generic_handle_irq() in acknowledges the event32 counter so interrupt goes away (eventually).33 34 - threaded handler of the device35 none36 37 - primary handler of the EP-interrupt38 reads the event and tries to process it. Everything that requires39 sleeping is handed over to the Thread. The event is saved in an40 per-endpoint data-structure.41 We probably have to pay attention not to process events once we42 handed something to thread so we don't process event X prio Y43 where X > Y.44 45 - threaded handler of the EP-interrupt46 handles the remaining EP work which might sleep such as waiting47 for command completion.48 49 Latency:50 51 There should be no increase in latency since the interrupt-thread has a52 high priority and will be run before an average task in user land53 (except the user changed priorities).54