On Monday 17 May 2010, Brian Swetland wrote: > On Mon, May 17, 2010 at 11:39 AM, Felipe Balbi <me@xxxxxxxxxxxxxxx> wrote: ... > > but can anyone write an app that holds a suspend_blocker ?? If so, then > > your goal is already broken, right ? I mean, if anyone can keep a > > suspend_blocker held forever, you'll never ever sleep, right ? While > > with runtime, if you keep the keypad open, only the keypad and the paths > > directly related to it (probably the i2c controller and the power domain > > where the i2c controller sits) will be kept alive, no ? > > No, you'll never suspend, which is different from never going to the > lowest CPU power state. On shipping Android devices we aggressively > completely power down the CPU in idle whenever we can (based on > latency requirements generally). We power off peripherals whenever > they're not in use. > > This is why I've stated previously that I don't think runtime PM and > opportunistic suspend are competitive features. Agreed. > Everyone who cares about minimizing power should want runtime pm or at least > similar functionality (our drivers have always powered down peripherals when > not in use, even while the device is open, etc, prior to the existence > of runtime PM). Yes. > If your environment is such that going to full suspend will not gain > you anything, then don't use opportunistic suspend. Exactly. > We find that there are savings to be had with this model in Android which is > why we use it. If you are going to use opportunistic suspend, > suspend_blockers provide useful functionality. And as I said, I regard this as a legitimate approach to power management. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
