Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Sat, 12 Nov 2016 00:34:47 +0100 | Subject | Re: [PATCH] PM / wakeirq: report wakeup events in dedicated wake-IRQs |
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On Fri, Nov 11, 2016 at 11:32 PM, Tony Lindgren <tony@atomide.com> wrote: > * Tony Lindgren <tony@atomide.com> [161111 14:29]: >> * Rafael J. Wysocki <rafael@kernel.org> [161111 13:33]: >> > On Fri, Nov 11, 2016 at 5:31 PM, Tony Lindgren <tony@atomide.com> wrote: >> > > * Rafael J. Wysocki <rafael@kernel.org> [161110 16:06]: >> > >> On Thu, Nov 10, 2016 at 7:49 PM, Brian Norris <briannorris@chromium.org> wrote: >> > >> > On Thu, Nov 10, 2016 at 10:13:55AM -0800, Dmitry Torokhov wrote: >> > >> >> On Thu, Nov 10, 2016 at 10:07 AM, Brian Norris <briannorris@chromium.org> wrote: >> > >> >> > It's important that user space can figure out what device woke the >> > >> >> > system from suspend -- e.g., for debugging, or for implementing >> > >> >> > conditional wake behavior. Dedicated wakeup IRQs don't currently do >> > >> >> > that. >> > >> >> > >> > >> >> > Let's report the event (pm_wakeup_event()) and also allow drivers to >> > >> >> > synchronize with these events in their resume path (hence, disable_irq() >> > >> >> > instead of disable_irq_nosync()). >> > >> >> >> > >> >> Hmm, dev_pm_disable_wake_irq() is called from >> > >> >> rpm_suspend()/rpm_resume() that take dev->power.lock spinlock and >> > >> >> disable interrupts. Dropping _nosync() feels dangerous. >> > >> > >> > >> > Indeed. So how do you suggest we get sane wakeup reports? Every device >> > >> > or bus that's going to use the dedicated wake APIs has to >> > >> > synchronize_irq() [1] in their resume() routine? Seems like an odd >> > >> > implementation detail to have to remember (and therefore most drivers >> > >> > will get it wrong). >> > >> > >> > >> > Brian >> > >> > >> > >> > [1] Or maybe at least create a helper API that will extract the >> > >> > dedicated wake IRQ number and do the synchronize_irq() for us, so >> > >> > drivers don't have to stash this separately (or poke at >> > >> > dev->power.wakeirq->irq) for no good reason. >> > >> >> > >> Well, in the first place, can anyone please refresh my memory on why >> > >> it is necessary to call dev_pm_disable_wake_irq() under power.lock? >> > > >> > > I guess no other reason except we need to manage the wakeirq >> > > for rpm_callback(). So we dev_pm_enable_wake_irq() before >> > > rpm_callback() in rpm_suspend(), then disable on resume. >> > >> > But we drop the lock in rpm_callback(), so can't it be moved to where >> > the callback is invoked? >> >> Then we're back to patching all the drivers again, no? > > Sorry I misunderstood, yeah that should work if rpm_callback() drops > the lock.
It still will not re-enable interrupts if the irq_safe flag is set. I wonder if we really care about this case, though.
Thanks, Rafael
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