linux-kernel - Re: [RESEND] [PATCH] Input: add appleir USB driver

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Date:	Mon, 4 Oct 2010 23:08:22 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Oliver Neukum <oliver@...kum.org>
Cc:	Bastien Nocera <hadess@...ess.net>,
	linux-input <linux-input@...r.kernel.org>,
	Jiri Kosina <jkosina@...e.cz>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND] [PATCH] Input: add appleir USB driver

On Tue, Oct 05, 2010 at 08:02:14AM +0200, Oliver Neukum wrote:
> Am Dienstag, 5. Oktober 2010, 06:45:20 schrieb Dmitry Torokhov:
> > > > +{
> > > > +   struct appleir *appleir = input_get_drvdata(dev);
> > > > +
> > > > +   mutex_lock(&appleir_mutex);
> > > > +
> > > > +   if (!(appleir->flags & APPLEIR_SUSPENDED)) {
> > > > +           usb_kill_urb(appleir->urb);
> > > > +           del_timer_sync(&appleir->key_up_timer);
> > > 
> > > You can close with a key unreleased.
> > 
> > I think this is handled by input core. We forcibly send release events
> > when device is disconnected; this takes care of surprise disconnect case.
> > OTOH if input_dev->close() is called that means that there are no more
> > listeners for the events so the fact that a key is still pressed is not
> > interesting to anyone.
> 
> But what about the next opener? He'll get a completely spurious
> key release event, as the next key is pressed.

How does the opening of a device handle relate to a device state?
Userspace should expect to see releases without presses (in case they
weren't the first client that opened the device).

But I guess we should reset the "last key" here, just in case.

> 
> > > > +           usb_kill_urb(appleir->urb);
> > > 
> > > If the system goes to sleep you'd better report a pressed key
> > > as released here and kill the timer.
> > 
> > Input core sends "release" events upon resume so we should be OK.
> 
> I see. OK, this is covered.

Might be a good idea to reset "last key" here as well. No need to send
2nd release event later on.

-- 
Dmitry
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