Messages in this thread | | | Date | Sun, 4 Dec 2011 00:50:38 -0800 | From | Dmitry Torokhov <> | Subject | Re: [PATCH v1] Input: tegra-kbc - report wakeup key for some platforms. |
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Hi Rakesh,
On Thu, Dec 01, 2011 at 01:09:59PM -0800, Rakesh Iyer wrote: > Hello Dmitry. > > Sorry for the wrap issue, my Outlook does not seem to obey the settings. > > I wanted to explain the tegra system resume path implementation so I can justify > why I am doing this complicated fix and why I feel it will guarantee the resume > is due to keypress. > > The tegra wake resume code is registered as a syscore ops. > When the system is resumed due to a wake event, the suspend_enter (after wakeup) > routine will invoke the tegra syscoreops_resume method and that routine will propagate > the wake event to the individual ISR's through genirq. > If kbc was wake source, kbc_isr will be invoked in this execution path. > > If system is resumed due to other reason, the tegra_syscoreops_resume code will not > find the event.
Consider the following sequence:
1. Something other than keyboard generates wakeup event 2. It's IRQ fires up and gets serviced 3. System starts resuming devices 4. User presses a key on the keypad while it is still suspended _and_ registered as a wakeup source 5. Keypad's ISR runs as well and you decide that KEY_POWER should be reported even though keypad wasn't the real reason the system woke up.
Is this scenario not possible?
Thanks.
-- Dmitry
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