On Mon, 2016-09-19 at 14:02 -0400, Alan Stern wrote: > > We can for sure enable autosuspend for the sdmmc device, although as > > soon as an SD card will be detected the rtsx driver will increase > the > > runtime PM usage count. The count is decreased when the card is > > removed (or failed to be initialized), thus runtime suspend is > > prevented as long as there is a functional card inserted. Testing autosuspend with card readers on usb_storage I saw a uniform response of reporting a medium change event upon resume. I am afraid other kinds of readers are not better in that regard. > > Which means that autosuspend matters only when a card isn't present, > and the host is polled every second or so to see whether a card has > been inserted. > > Under those circumstances you probably don't want to use > autosuspend. > That is, resuming before each poll and suspending afterward may use > less energy than staying at full power all the time. Is that based on concrete figures about power consumption? And it seems to me that we need a way to indicate that the heuristics should not be used, but a device immediately suspended. The timer is sensible only if the next wakeup is unknown. Regards Oliver -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
