The measurement that made this worth building: gpio75 is silent at idle under
WAIT_TOUCH -- zero edges in sixty seconds -- and bursts within milliseconds of
a finger landing. In the observed taps the burst appeared in the transcript
hundreds of milliseconds before the polled capture noticed the finger, which is
why a quick tap only ever produced one frame however cheap the frame became.
So the inter-frame wait is now a wait on the line rather than a sleep. At idle
it times out at the fallback cadence and costs nothing. At contact it returns
at once, so the first capture of a press happens when the finger lands. While
the finger stays down the sensor keeps pulsing, so the wait keeps returning
immediately and the loop runs as fast as QTEE allows -- which is what a press
wants and what stock's architecture does.
Queued edges are dropped when a session arms, or the previous press's burst
would wake the first wait instantly. --edge-wake gates it as a single variable
against the labelled 2-of-10 baseline; it and --irq-observe are mutually
exclusive because both would drain the same fd.
Jorijn van der Graaf
578e2321fa