Re: [PATCH v4 1/2] Input: enable i8042-level wakeup control

On Wed, Aug 03, 2011 at 08:24:46PM +0100, Daniel Drake wrote:

On Wed, Aug 3, 2011 at 7:43 PM, Dmitry Torokhov
[off-list ref] wrote:

quoted

No, I do not believe we can do what you are doing in input core. You are
changing behavior for one platform and one (or 2 drivers) that will not
be matched (at least I don't think so) by anything else out there. What
will happen if you plug a random USB keyboard into OLPC box? Will it keep
leds powered?

In all other cases, behaviour is unchanged. The input device is not
marked as wakeup capable, therefore the user cannot mark it as
wakeup-enabled, therefore this code does not execute.

So a USB keyboard on an OLPC laptop would behave exactly as it does
before this patch, as would devices on other systems.

The only way this functionality gets enabled is at the code level (as
it does in patch 2/2), and then once the user has requested wakeups on
all devices in the chain.

I believe we can and do mark devices such as USB as wakeup capable on
other arches, you do not have control here. That is why I am uneasy with
doing this in input core.

quoted

quoted

quoted

Does the controller wakes up the system on key release or only press? My
concern is with cases when we suspend with a key pressed and wake up
with it already released.

It wakes up on key press, but our EC buffers communication, so both
the key press and key release event would be delivered in the above
scenario.

Just to confirm, we 3 events will be delivered in this case:

Sorry, I misunderstood the question and answered "what happens if the
system is sleeping and you press and quickly release a key before the
system is fully running" - in which case the system wakes up and
delivers both events.

For the question you asked, regarding a key being pressed as the
system goes into suspend, the system wakes up from suspend
immediately.
I just tested this by holding the 'i' key down while going into suspend.
While the key is being held down, the system receives repeated
interrupts with data 0x17 ('i' key pressed). The system suspends, but
then immediately wakes up, and continues the flood of 0x17 interrupts.
When I release the key a few seconds later, a 0x97 ('i' released)
interrupt arrives.

Is there any keys that are not autorepeating. For example regular
(non-OLPC) laptops usually do not repeat suspend and other special keys.
In fact, they quite often forget to send release events for them ;)

I guess the more accurate way to describe the wakeup condition is that
it wakes up on any i8042 interrupt.

quoted

I also wonder what will happen with non-PS2 devices...

Again - other devices are not affected.

quoted

Instead of wiring it all through input core could we contain this in
atkbd and hgpk by registering pm_notifiers and ignoring certain requests
from input/serio cores during system state transition on OLPC only?

I'll look into this, thanks for the suggestion.

Much appreciated, sorry for being a pain.

-- 
Dmitry