Re: Wakeup-events implementation

David Brownell
2010-08-17T18:37:22Z

--- On Tue, 8/17/10, Alan Stern <stern@rowland.harvard.edu> wrote:

I wasn't
> aware that memory cards could generate wakeup events.

Almost all MMC/SD hardware can generate reliable
insert/remove events, in my experience. So MMC/SD
drivers I've modified tend to treat them as wake
events ... userspace can respond without polling
constantly "did it change yet, huh, did it???"

Unfortunately Pierre spent a lot of time hard-wiring
UNSAFE_RESUME assumptions into the MMC core, so lots
of that stuff is currently (and needlessly) broken.

And of more experimental interest, something I don't
recall being discussed here: I/O completions as
wake events. Start an I/O, enter low power state,
and wake when it completes. Easily done on lots of
embedded hardware..