Re: [PATCH 0/2] power button repeat input events

[Denis Karpov <ext-denis.2.karpov@nokia.com>]

On Mon, Mar 14, 2011 at 05:10:22PM +0530, ext Menon, Nishanth wrote:
> Date: Mon, 14 Mar 2011 17:10:22 +0530
> From: "ext Menon, Nishanth" <nm@ti.com>
> To: Denis Karpov <ext-denis.2.karpov@nokia.com>
> CC: tony@atomide.com, linux-omap@vger.kernel.org
> Subject: Re: [PATCH 0/2] power button repeat input events
> In-Reply-To: <20110314111327.GA10563@smart.research.nokia.com>
> 
> On Mon, Mar 14, 2011 at 16:43, Denis Karpov
> <ext-denis.2.karpov@nokia.com> wrote:
> >
> > On Fri, Mar 11, 2011 at 10:25:27PM +0530, ext Nishanth Menon wrote:
> > >
> > > Denis Karpov wrote, on 03/11/2011 10:07 PM:
> > > >Hi,
> > > >
> > > >this patchset adds optional generation of repeat input events for
> > > >twl4030 power button. It adds optional platform data for
> > > >twl4030-pwrbutton and initializes it for RX51/N900 (default
> > > >behavior kept - repeated input events disabled).
> > > >
> > > >We are working on an OMAP3 with TWL5031 MFD. In one of the use
> > > >scenarios userspace wants to receive repeated input events from
> > > >long press of power button.
> > >
> > > dumb question - is'nt this a userspace responsibility as far as power
> > > button is concerned? what is the benefit of providing repeat events
> > > like a generic keypad for the power button?
> >
> > In our case userspace needs this to track the continuous button press
> > of power button.
> thanks for your explanation, but a follow on dumb question:
> include/linux/input.h
> #define KEY_POWER               116     /* SC System Power Down */
> 
> in twl-powerbutton.c, I see:
> input_report_key(pwr, KEY_POWER, value & PWR_PWRON_IRQ);
> where value is the value from the register status, should'nt we get
> two events? one on press and one on release after say 10 mins(assuming
> person keeps it pressed for 10 mins?
> 
> Is there different behavior we intend to implement in userspace which
> differentiates 1 KEY_POWER event Vs 10 KEY_POWER event?

No, but due to specifics of userspace sw components involved it seems  
not to be possible to reliably save the state for power button to detect 
long keypresses.

I thought that this change if implemented as optional feature and 
localized to scpecific devices/boards would not hurt. 
twl-keypad.c implements exactly same behavior for keypad keys, why not 
to do this for the power key ?

Denis