Re: [PATCH 0/2] input: mt: Add helper function to send end events

From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: Henrik Rydberg <rydberg@euromail.se>
Cc: "Felipe F. Tonello" <eu@felipetonello.com>,
	linux-input@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/2] input: mt: Add helper function to send end events
Date: Tue, 31 Dec 2013 10:50:36 -0800	[thread overview]
Message-ID: <20131231185035.GD6897@core.coreip.homeip.net> (raw)
In-Reply-To: <52C28DC7.9020003@euromail.se>

Hi Henrik,

On Tue, Dec 31, 2013 at 10:26:31AM +0100, Henrik Rydberg wrote:
> Hi Felipe,
> 
> > Adds a helper function to send end touch events for active tracking ids.
> > And also implements it in egalax driver.
> 
> What problematic scenario is this supposed to solve?
> 
> The 'release on suspend' is only an approximation to the 'close
> laptop' scenario, it is certainly not correct in the coffee table
> case,

Why would it not be correct for coffee table? Do we expect the touches
to remain valid while the device is asleep?

> for instance. Instead of
> hardcoding this in the kernel, userland can easily detect long intervals
> directly using the event time.

But with slots it is not only problem with old events being sent out
later, it is that we have mix of old (pre-sleep) and new state.

> 
> Unless there is already a reasonable mechanism in your user
> application which deals with cases like this but fails to account for
> your particular problem scenario, the patch will not be applied.
> 

We do that for keys (release them when we transition to system sleep)
and I think it might be worthwhile to do the same for touch data.

Thanks.

-- 
Dmitry