Re: [PATCH] PM / wakeirq: report wakeup events in dedicated wake-IRQs

From: Pavel Machek
Date: Thu Nov 10 2016 - 15:57:26 EST


On Thu 2016-11-10 10:07:07, Brian Norris 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()).
>
> Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx>

How is this supposed to be presented to userspace?

There was big flamewar about that some time ago, and "what woke up the
system" is pretty much meaningless, and certainly unavailable on most
PC class hardware. Good question to ask is "what wakeup events
happened while the userspace was not available"....

Pavel

--
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