On Wed, 2 Jun 2010, Arve Hjønnevåg wrote: > 2010/6/2 Thomas Gleixner <tglx@xxxxxxxxxxxxx>: > > On Wed, 2 Jun 2010, Arve Hjønnevåg wrote: > >> 2010/6/2 Neil Brown <neilb@xxxxxxx>: > >> > There would still need to be some sort of communication between the the > >> > suspend daemon on any event daemon to ensure that the events had been > >> > processed. This could be very light weight interaction. The point though is > >> > that with this patch it becomes possible to avoid races. Possible is better > >> > than impossible. > >> > > >> > >> We already have a solution. I don't think rejecting our solution but > >> merging a worse solution should be the goal. > > > > That's not the goal at all. We want a solution which is acceptable for > > android and OTOH does not get into the way of other approaches. > > > > I don't actually think the suspend blocker patchset get in the way of > anything else. > > > The main problem I have is that suspend blockers are only addressing > > one particular problem space of power management. > > > > We have more requirements than that, e.g. an active device transfer > > requires to prevent the idle code to select a deep power state due to > > latency requirements. > > > > So we then have to implement two mechanisms in the relevant drivers: > > > > 1) telling the idle code to limit latency > > 2) telling the suspend code not to suspend > > And 3) telling the idle code to not enter low power modes that disrupt > active interrupts or clocks. > > Our wakelock code handles 2 and 3, but I removed support for 3 on > request since you can hack it by specifying a latency value that you > know the low power mode cannot support. You are mixing concepts. clock domains and power domains are a separate issue which are already handled by the run time power management code and the clock framework. The interrupt latency is a QoS requirement and has nothing to do with power domains and clock domains simply because I can go deeper w/o violating the clock and power domain constraints when the latency allows it. > > My main interest is to limit it to one mechanism, which is QoS based > > and let idle and suspend make the appropriate decisions based on that > > information. > > > > We can use one mechanism for this, but we still have to specify both. > To me this is just another naming argument and not a good reason to > not merge the suspend blocker code. You have to modify the same The main objection against suspend blocker is the user space interface / ABI issue, not the driver code which we can fix in no time. But we cannot fix it once it is glued into a user space interface. I don't care about adding two empty static inlines into a header file, which allows to merge the android drivers, but I care much about giving a guaranteed behaviour to user space. Thanks, tglx
