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Diffstat (limited to 'Documentation/usb/dwc3.txt')
-rw-r--r-- | Documentation/usb/dwc3.txt | 45 |
1 files changed, 0 insertions, 45 deletions
diff --git a/Documentation/usb/dwc3.txt b/Documentation/usb/dwc3.txt deleted file mode 100644 index 1d02c01d1c7..00000000000 --- a/Documentation/usb/dwc3.txt +++ /dev/null | |||
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1 | |||
2 | TODO | ||
3 | ~~~~~~ | ||
4 | Please pick something while reading :) | ||
5 | |||
6 | - Convert interrupt handler to per-ep-thread-irq | ||
7 | |||
8 | As it turns out some DWC3-commands ~1ms to complete. Currently we spin | ||
9 | until the command completes which is bad. | ||
10 | |||
11 | Implementation idea: | ||
12 | - dwc core implements a demultiplexing irq chip for interrupts per | ||
13 | endpoint. The interrupt numbers are allocated during probe and belong | ||
14 | to the device. If MSI provides per-endpoint interrupt this dummy | ||
15 | interrupt chip can be replaced with "real" interrupts. | ||
16 | - interrupts are requested / allocated on usb_ep_enable() and removed on | ||
17 | usb_ep_disable(). Worst case are 32 interrupts, the lower limit is two | ||
18 | for ep0/1. | ||
19 | - dwc3_send_gadget_ep_cmd() will sleep in wait_for_completion_timeout() | ||
20 | until the command completes. | ||
21 | - the interrupt handler is split into the following pieces: | ||
22 | - primary handler of the device | ||
23 | goes through every event and calls generic_handle_irq() for event | ||
24 | it. On return from generic_handle_irq() in acknowledges the event | ||
25 | counter so interrupt goes away (eventually). | ||
26 | |||
27 | - threaded handler of the device | ||
28 | none | ||
29 | |||
30 | - primary handler of the EP-interrupt | ||
31 | reads the event and tries to process it. Everything that requires | ||
32 | sleeping is handed over to the Thread. The event is saved in an | ||
33 | per-endpoint data-structure. | ||
34 | We probably have to pay attention not to process events once we | ||
35 | handed something to thread so we don't process event X prio Y | ||
36 | where X > Y. | ||
37 | |||
38 | - threaded handler of the EP-interrupt | ||
39 | handles the remaining EP work which might sleep such as waiting | ||
40 | for command completion. | ||
41 | |||
42 | Latency: | ||
43 | There should be no increase in latency since the interrupt-thread has a | ||
44 | high priority and will be run before an average task in user land | ||
45 | (except the user changed priorities). | ||