forked from Minki/linux
46 lines
1.8 KiB
Plaintext
46 lines
1.8 KiB
Plaintext
|
|
||
|
|
TODO
|
||
|
|
~~~~~~
|
||
|
|
Please pick something while reading :)
|
||
|
|
|
||
|
|
- Convert interrupt handler to per-ep-thread-irq
|
||
|
|
|
||
|
|
As it turns out some DWC3-commands ~1ms to complete. Currently we spin
|
||
|
|
until the command completes which is bad.
|
||
|
|
|
||
|
|
Implementation idea:
|
||
|
|
- dwc core implements a demultiplexing irq chip for interrupts per
|
||
|
|
endpoint. The interrupt numbers are allocated during probe and belong
|
||
|
|
to the device. If MSI provides per-endpoint interrupt this dummy
|
||
|
|
interrupt chip can be replaced with "real" interrupts.
|
||
|
|
- interrupts are requested / allocated on usb_ep_enable() and removed on
|
||
|
|
usb_ep_disable(). Worst case are 32 interrupts, the lower limit is two
|
||
|
|
for ep0/1.
|
||
|
|
- dwc3_send_gadget_ep_cmd() will sleep in wait_for_completion_timeout()
|
||
|
|
until the command completes.
|
||
|
|
- the interrupt handler is split into the following pieces:
|
||
|
|
- primary handler of the device
|
||
|
|
goes through every event and calls generic_handle_irq() for event
|
||
|
|
it. On return from generic_handle_irq() in acknowledges the event
|
||
|
|
counter so interrupt goes away (eventually).
|
||
|
|
|
||
|
|
- threaded handler of the device
|
||
|
|
none
|
||
|
|
|
||
|
|
- primary handler of the EP-interrupt
|
||
|
|
reads the event and tries to process it. Everything that requries
|
||
|
|
sleeping is handed over to the Thread. The event is saved in an
|
||
|
|
per-endpoint data-structure.
|
||
|
|
We probably have to pay attention not to process events once we
|
||
|
|
handed something to thread so we don't process event X prio Y
|
||
|
|
where X > Y.
|
||
|
|
|
||
|
|
- threaded handler of the EP-interrupt
|
||
|
|
handles the remaining EP work which might sleep such as waiting
|
||
|
|
for command completion.
|
||
|
|
|
||
|
|
Latency:
|
||
|
|
There should be no increase in latency since the interrupt-thread has a
|
||
|
|
high priority and will be run before an average task in user land
|
||
|
|
(except the user changed priorities).
|