What's the difference between event_bits and change_bits?
I just cannot understand why we need two variables.
188 struct usb_hub {
...
205 unsigned long event_bits[1]; /* status
change bitmask */
206 unsigned long change_bits[1]; /* ports with
logical connect
207 status change */
Take following section for example,inside hub_events() sampled from
drivers/usb/core/hub.c:
2594 /* deal with port status changes */
2595 for (i = 0; i < hub->descriptor->bNbrPorts; i++) {
2596 connect_change = test_bit(i, hub->change_bits);
2597 if (!test_and_clear_bit(i+1, hub->event_bits) &&
2598 !connect_change)
2599 continue;
Why do we need to test changes_bits and then test event_bits?
Regards
Jason
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