and if it has been configured to generate interrupts (see the
description of "edge"), you can poll(2) on that file and
poll(2) will return whenever the interrupt was triggered. If
- you use poll(2), set the events POLLPRI and POLLERR. If you
- use select(2), set the file descriptor in exceptfds. After
- poll(2) returns, either lseek(2) to the beginning of the sysfs
- file and read the new value or close the file and re-open it
- to read the value.
+ you use poll(2), set the events POLLPRI. If you use select(2),
+ set the file descriptor in exceptfds. After poll(2) returns,
+ either lseek(2) to the beginning of the sysfs file and read the
+ new value or close the file and re-open it to read the value.
"edge" ... reads as either "none", "rising", "falling", or
"both". Write these strings to select the signal edge(s)