linux-kernel - Re: [PATCH v2 1/3] platform: x86: dell-rbtn: Dell Airplane Mode Switch driver

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Message-Id: <201505021713.11503@pali>
Date:	Sat, 2 May 2015 17:13:11 +0200
From:	Pali Rohár <pali.rohar@...il.com>
To:	Gabriele Mazzotta <gabriele.mzt@...il.com>
Cc:	Alex Hung <alex.hung@...onical.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Darren Hart <dvhart@...radead.org>,
	"platform-driver-x86@...r.kernel.org" 
	<platform-driver-x86@...r.kernel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] platform: x86: dell-rbtn: Dell Airplane Mode Switch driver

On Saturday 02 May 2015 15:51:50 Gabriele Mazzotta wrote:
> On Thursday 30 April 2015 09:44:29 Pali Rohár wrote:
> > On Thursday 30 April 2015 14:06:27 Alex Hung wrote:
> > > Method ABRT is to be used by driver to disable BIOS
> > > handling of radio button. So the changes in behaviours
> > > observed by Gabriele is expected. I have seen other
> > > systems behave the same way.
> > 
> > Right, that after that ARBT call operating system get full
> > control over radio devices and ACPI/BIOS will not
> > automatically enable/disable them. I think this is OK.
> > 
> > But for that we need also support for manually
> > enable/disable radio devices and code for this support is
> > missing. Or do DELLABCE/RBTN acpi devices somehow support
> > enabling/disabling it via system/kernel request?
> > 
> > > I do also see firmware only sends Notify(RBTN, 0x80) and
> > > no hard block whether ABRT(1) is called or not.  Thus
> > > keycode are the only option on those machines.
> > 
> > Key is ok, but we *must* have ability to hard block it via
> > some ACPI/WMI/BIOS/FW/etc... call. Otherwise ARBT(1) is no
> > go as users should be able to enable/disable their radio
> > devices (bluetooth for powersave)
> > 
> > > The idea to have an option (kernel parameter) for calling
> > > ABRT is great. I can help verify on more machines. Is
> > > Gabriele's patch above a final version that I should
> > > test?
> > 
> > No, I do not think so. This looks like hack or pure design.
> > Kernel option could be there, but just for buggy BIOSes
> > (and future changed design).
> > 
> > But now it looks like for correct work is specifying that
> > param required -- which is bad.
> > 
> > Alex, can you ask Dell people how should system turn off e.g
> > bluetooth or wifi device if ARTB(1) is called and
> > system/kernel (instead ACPI) is expected to turn off/on
> > blueooth (and wifi) devices?
> 
> I completely forgot that libsmbios comes with
> smbios-wireless-ctl. It allows me to control the hardware
> slider.
> 
> > I think that without this information (and working driver
> > for it) we should not enable ARTB(1) or including this
> > driver into kernel tree as it will break some existing
> > machines...
> 
> Alex, could you test smbios-wireless-ctl and see what it says
> about the laptops with no hardware slider? For instance on
> mine it says:
> 
> Radio Status for WLAN:
>         WLAN enabled at boot
>         WLAN supported
>         WLAN enabled
>         WLAN installed
>         WLAN boot-time wireless switch setting not present
>         WLAN runtime switch control currently enabled
>         Status Code: 0
> 
> You can find the utility here:
> http://linux.dell.com/git/libsmbios.git
> 
> The code to check for the presence of an hardware slider is
> even already implemented in dell-laptop and works on my
> laptop, it says the slider is present.
> 
> 
> Pali, you have a Latitude, right? Is "whitelisted" true when
> you load dell-laptop? I'm asking because when I load
> dell-laptop with force_rfkill, my function key stops working.
> Radio devices get disabled the moment dell-laptop is loaded
> and I must use smbios-wireless-ctl to re-enable them. Once I
> re-enabled them, the function keys starts working again.
> I don't know exactly what happens on your laptop, but I was
> wondering if dell-laptop is messing things up on your laptop
> too.

Hi, on my Latitude E6440 machine dell-laptop (with rfkill) 
working fine. There is no problem with it.

-- 
Pali Rohár
pali.rohar@...il.com

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