linux-kernel - Re: [PATCH 0/3] Dell Airplane Mode Switch driver

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Message-ID: <2697957.miSb4Rm7HK@xps13>
Date:	Fri, 05 Dec 2014 22:49:11 +0100
From:	Gabriele Mazzotta <gabriele.mzt@...il.com>
To:	Pali Rohár <pali.rohar@...il.com>
Cc:	Darren Hart <dvhart@...radead.org>,
	Alex Hung <alex.hung@...onical.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	"platform-driver-x86@...r.kernel.org" 
	<platform-driver-x86@...r.kernel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/3] Dell Airplane Mode Switch driver

On Friday 05 December 2014 22:23:25 Pali Rohár wrote:
> On Friday 05 December 2014 22:12:42 Gabriele Mazzotta wrote:
> > On Friday 05 December 2014 22:03:24 Pali Rohár wrote:
> > > On Friday 05 December 2014 21:53:10 Gabriele Mazzotta wrote:
> > > > On Friday 05 December 2014 21:38:17 Pali Rohár wrote:
> > > > > On Wednesday 03 December 2014 14:00:23 Darren Hart wrote:
> > > > > > On Thu, Dec 04, 2014 at 10:55:32AM +0100, Pali Rohár 
> wrote:
> > > > > > > Darren, I think that if we do not solve problem with
> > > > > > > duplicate key events (in dell-wireless.c) we should
> > > > > > > postpone these patches to later kernel version. It
> > > > > > > is better to not have such regression as it confuse
> > > > > > > software like NetworkManager which is widely used.
> > > > > > 
> > > > > > OK, that's what I needed. Thanks. Ignore my previous
> > > > > > request, you answered it here. I will drop
> > > > > > dell-wireless.c and look for a combined solution from
> > > > > > you and Alex for the next release.
> > > > > > 
> > > > > > Thanks,
> > > > > 
> > > > > And according to discussion about Side effect of
> > > > > pressing special keys at [1] [2] we should not report
> > > > > this wireless key event (as input device) to userspace.
> > > > > And Alex's driver is doing that.
> > > > > 
> > > > > [1] -
> > > > > http://www.spinics.net/lists/platform-driver-x86/msg0592
> > > > > 2.h tml [2] -
> > > > > http://www.spinics.net/lists/platform-driver-x86/msg0592
> > > > > 4.h tml
> > > > 
> > > > Alex's patch is for those laptop whose BIOS only sends a
> > > > notification to DELLABCE when Fn keys are pressed. His
> > > > patch simply translates these ACPI notifications to
> > > > KEY_RFKILL keypresses.
> > > 
> > > Yes, and your last patch disables sending such KEY events to
> > > userspace (in dell-wmi driver). BIOS already handle changes,
> > > so key press should not be reported to userspace... [1]
> > > (from previous email).
> > 
> > This is not true if ARBT (with 1 as parameter) is called. When
> > this is done, the BIOS stops managing the radio devices
> > completely and reporting KEY_RFKILL to userspace becomes a
> > necessity. I guess that the laptops on which this patch was
> > tested behaved like mine after ARBT is called, given that the
> > call was missing completely in the original patch.
> > 
> 
> Ok. It means that at least original Alex patch needs to be 
> reworked (so we will do not see duplicate events problem and 
> problem described in previous email).
> 
> But my other question is... If ARBT(1) is called then it disables 
> BIOS support for managing radio devices on your laptop. Why we 
> need patch which disabling useful functionality (= ability to 
> disable wifi rfkill)? We still do not have patch which can 
> correctly set rfkill state by software on laptops of your fn key 
> type.

That's what happens on my laptop, but Alex said that the laptops on
which he worked, ARBT was empty, so I guess it's not always a choice.
In order not to break things, all the laptops that support both the
methods must be set to the correct mode through ARBT when the module
is loaded. If this is not done, then what you say is correct, we should
not report KEY_RFKILL, or at least do it selectively, but I guess that
this is not be possible without a whitelist (that we don't have).

> > > > Correct if I'm wrong, but shouldn't his patch have no
> > > > effects on your laptop? If I'm not wrong, CRBT returns 2
> > > > on your laptop, so the input device is not even created.
> > > > Am I missing something?
> > > > 
> > > > Gabriele
> > > 
> > > Yes, it has no effect for my laptop.
> 
> 

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