PATCH/RFC [0/3]: Fix suspend and other acceleromter issues

Werner Almesberger werner at
Sun Nov 16 13:54:47 CET 2008

Simon Kagstrom wrote:
> Well, the interesting thing which I noticed with the level-triggered
> interrupts was that using no threshol (data ready interrupts) are a lot
> less invasive (time is mostly spent in userspace) than using the small
> threshold (when >90% of the time is spent handling interrupts).

Just to be clear: is what you're seeing here expected behaviour because
you asked for an interrupt on every slight change ? Or do you think the
number of interrupts is too large for the changes you get ?

It seems that the best combination for games would be a threshold AND
a period. That way, you don't get interrupts until something has
actually happened, and at the same time you're protected against user
space getting starved by a flood of them (hmm, that's where the
metaphor breaks down :-)

The AOI bit in FF_WU_CFG_x seems to be able to do just that.

- Werner

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