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Date:	Wed, 24 Dec 2014 17:13:45 +0800
From:	Alex Hung <>
To:	Gabriele Mazzotta <>
Cc:	Pali Rohár <>,
	Darren Hart <>,
	Matthew Garrett <>,
Subject: Re: [PATCH 0/3] Dell Airplane Mode Switch driver

I uploaded acpidump files [1] (except for XPS 13 which is not
available), and this should help clarify what has been tested.

Does Inspirion 5721 does not have either DELLABCE or DELRBTN. It is
used for comparison. My apologies that I did not point this out in
previous email.

When calling ARBT(1), BIOS will no longer issue scancode and will not
pull low hardware pin "W_DISABLE#" on mini card. This essentially
gives all wireless control to OS. This is likely the answer to
Microsoft's Windows Certification Program
System.Client.RadioManagement.HardwareButton [2] as below:

If a PC has a physical (hardware) button switch on a PC that turns
wireless radios on and off, it must be software controllable and
interact appropriately with the Radio Management UI

Dell's BIOS does issue a notify(RBTN, 0x80). This is done purposely to
re-enumerate the state of radio switch which may be changed when
system is in S3 or S4. I think this should not occur when CRBT returns
0 or 1 (for hotkey that cannot be changed during S3 or S4), but that's
how it is done currently.

dell-wireless does not handle this notification in S3 or S4 for
following reasons:

1. dell-wireless does not handle slider (i.e. CRBT = 2 or 3). Device
drivers should read the hardware pin, "W_DISABLE#" on mini spec and
change hard block accordingly. This pin is commonly used by OEM today.

2. it is not possible to distinguish the notification (0x80) from
hotkey press or S3/S4. I also concerned this may mis-trigger state
change when resuming from S3 or S4, but it does not. Does any know how
to ignore this notification during resume only?

dell-rbtn can use this notification + method (GRBT) [2] to solve the
problem that slider state.

[3] It seems GRBT may not always be implemented...

I'd love to do more tests and share the results on any particular
systems, but I may need some more detailed instructions.

On Tue, Dec 23, 2014 at 3:16 AM, Gabriele Mazzotta
<> wrote:
> On Monday 22 December 2014 15:27:57 Alex Hung wrote:
>> = Testing =
>> I tested six Dell systems for two sets of patches for dell radio
>> button - two system with radio slider and four with radio hotkey.
>> There are also two systems with working ARBT method.
>> == Basic Information ==
>> Based OS: Ubuntu 14.10 (kernel 3.16 [1]) and kernel 3.18 [2]
>> Patches:
>> 1. dell-wireless v3 = original v2 + Gabriele's suggestion [3]
>> 2. dell-rbtn [4]
>> Method:
>> 1. run "rfkill list" and press hotkey / toggle slider during runtime
>> 2. run "rfkill list" and toggle slider during S3
>> == Results ==
>> I summarized the tests in Google sheet as below. Please advise if
>> anyone has problem reading it.
>> PS. The document will stay as long as possible for future references.
>> == Summary ==
>> 1. I did not observed a duplicated event. However, keycode 240
>> (unknown) is generated on many UUT. It is not issued by dell-laptop or
>> del-wmi. I am suspecting it is the other event Pali observes but it
>> can be the result of different distro.
>> 2. Some system issues scancode "0xe0 0x73 0xe0 0xf3". It can also be
>> used toggle wireless state but this can also be distro-dependent. This
>> scancode does nothing on Ubuntu 14.10.
>> 2. There are two systems with working ARBT (XPS 13 9333 and Inspiron
>> 7447). Calling ARBT(1) changes BIOS behaviours, and this matches to
>> Dell's document. We should include it in the patch for maximum
>> capability.
>> [1] dell-wireless is only tested 3.16.
>> [2] dell-rbtn is tested on 3.16 and 3.18, but no differences are observed.
>> [3]
>> [4]
> I've just tried the last revision of dell-wireless and noticed that a
> notification (0x80) is sent to DELLABCE after a transition from S3 to
> S0, causing dell-wireless to send KEY_RFKILL. This shouldn't happen.
> Same thing for transitions from S4 to S0.
> Gabriele

Alex Hung
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