[PATCH] fix-lis302dl-isr-lock.patch
joerg
joerg.twinklephone at gmx.de
Mon Mar 31 21:19:01 CEST 2008
Another common usage for edge IRQ is to count spikes. What all these
situations have in common: they don't reset an external latch.
CPU internal edge latch usually is reset by reading the register (so maybe
that's where these got lost, if some other task was reading it).
If the external device needs attention during ISR to reset the line, this
always means level is the way to go. (imagine accel triggered an edge IRQ,
and when you eventually try to service it, it's powered down meanwhile. There
are many ways to miss an edge or catch a surplus one. Level never
fails/always recovers)
j
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