On Tue, 17 Aug 2010, David Brownell wrote: > --- On Tue, 8/17/10, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> 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???" This is interesting in light of the fact that testing has shown many USB card readers don't track insert/remove events while in low-power mode. When they return to full power, if a card is present they always report a media change -- even if the card had been there all along. This makes autosuspend less useful than it might be. > 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. There's a difference between generating wakeup events for insert/remove and keeping track of media-change events. I wouldn't want my sleeping laptop to wake up when I insert or remove a memory card, but I would like it to recognize when a card has been changed. If the hardware can do one but not the other then Pierre's choice is understandable (although not in accord with Linus's preference). Alan Stern _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
