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. > > 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 drivers if you call suspend_block() as if you call pm_qos_update_requirement(don't suspend). We have to specify when it is not safe to suspend independent of when it is not safe to enter low power idle modes so unless you want to have a bitmap of constraints you don't save any calls. And, if we later get a constraint framework that supports everything, we can switch to it then and we will then already have some drivers annotated. -- Arve Hjønnevåg -- 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
