RE: [PATCH v1] Input: tegra-kbc - report wakeup key for some platforms.

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.

In the kbc we ignore all keypresses until kbc_resume re-enables the fifo interrupt.
So the only way to generate this key would be if the tegra_syscoreops_resume 
finds that kbc was wake source

Maybe my understanding is wrong. Please feel free to correct me.

Regards
Rakesh

-----Original Message-----
From: Dmitry Torokhov [mailto:dmitry.torokhov@gmail.com]
Sent: Wednesday, November 30, 2011 11:27 PM
To: Rakesh Iyer
Cc: rydberg@euromail.se; Stephen Warren; Laxman Dewangan; linux-
kernel@vger.kernel.org; linux-input@vger.kernel.org; linux-tegra@vger.kernel.org
Subject: Re: [PATCH v1] Input: tegra-kbc - report wakeup key for some platforms.

On Wed, Nov 30, 2011 at 02:14:03PM -0800, Rakesh Iyer wrote:

quoted

Thanks Dmitry.

Since there can be multiple wake causes I wanted to isolate wake key
generation to the case where keyboard actually generated the wake
interrupt.

I do not think you can guarantee this though because if user touches
keyboard "too early", before your resume method had a chance to disable
kbc interrupt as a wakeup source, you are still going to get that
interrupt and deliver KEY_POWER even though KBC is not the actual wakeup
source.

So don't over-complicate it. If hardware can't detect actual key pressed
just emit KEY_POWER if a key was at any time between calls to
tegra_kbc_suspend() and tegra_kbc_resume().

BTW, could you please have your MUA wrap long lines around 75 column or so?

Thanks.

--
Dmitry