On Sat, 20 Aug 2011, Mark Brown wrote: > On Fri, Aug 19, 2011 at 10:24:19PM -0400, Alan Stern wrote: > > On Sat, 20 Aug 2011, Mark Brown wrote: > > > > interfaces and let the subsystem and driver translate these into actual > > > wakeup latency constraints: > > > > https://lists.linux-foundation.org/pipermail/linux-pm/2011-August/032422.html > > > https://lists.linux-foundation.org/pipermail/linux-pm/2011-August/032428.html > > > > This is much easier for users as it translates into something they're > > > actually doing (and in most cases the driver can make it Just Work) and > > > it means that off the shelf applications will end up tuning the system > > > appropriately by themselves. I'm additionally concerned that if we > > > expose this stuff directly to userspace that's an open invitation to > > > driver authors to not even bother trying to make the kernel figure this > > > stuff out by itself and to instead tie the system together with magic > > > userspace. > > > Can you give a couple of examples to illustrate these points? I think > > it would help a lot to make the conversation more concrete. > > Examples of what? Latency constraints from drivers? That'd be things > like Kevin listed in the second message linked above - the kernel knows > it needs to wake up within a given time period in order to have time to > do what it needs to do in response to a given wake source such as > filling a buffer before it underflows. No, I as wasking about driver- and subsystem-specific interfaces to userspace that translate into things users are already doing. Kevin's example was a touchscreen (although that was really an example of setting a power usage level, not a latency constraint). Do you have any others? Alan Stern -- 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
