On Monday, March 12, 2012, Linus Walleij wrote: > On Fri, Mar 9, 2012 at 12:01 AM, Rafael J. Wysocki <rjw@xxxxxxx> wrote: > > > A runtime suspend of a device (e.g. an MMC controller) belonging to > > a power domain or, in a more complicated scenario, a runtime suspend > > of another device in the same power domain, may cause power to be > > removed from the entire domain. In that case, the amount of time > > necessary to runtime-resume the given device (e.g. the MMC > > controller) is often substantially greater than the time needed to > > run its driver's runtime resume callback. That may hurt performance > > in some situations, because user data may need to wait for the > > device to become operational, so we should make it possible to > > prevent that from happening. > > > > For this reason, introduce a new sysfs attribute for devices, > > power/pm_qos_resume_latency_us, allowing user space to specify the > > upper bound of the time necessary to bring the (runtime-suspended) > > device up after the resume of it has been requested. However, make > > that attribute appear only for the devices whose drivers declare > > support for it by calling the (new) dev_pm_qos_expose_latency_limit() > > helper function with the appropriate initial value of the attribute. > > > > Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx> > > Reviewed-by: Kevin Hilman <khilman@xxxxxx> > > Reviewed-by: Mark Brown <broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx> > > Acked-by: Linus Walleij <linus.walleij@xxxxxxxxxx> Thanks! Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
