Re: [PATCH v5 5/5] dell-rbtn: Add a comment about the XPS 13 9350

["Pali Rohár" <pali.rohar@gmail.com>]

On Wednesday 17 February 2016 07:07:28 Mario Limonciello wrote:
> 
> 
> On 02/17/2016 05:16 AM, Pali Rohár wrote:
> > On Monday 15 February 2016 08:32:37 Andy Lutomirski wrote:
> >> On the XPS 13 9350, the dell-rbtn mechanism has a new device id, and
> >> the DSDT turns it off if a new enough _OSI is supported.  Add a
> >> comment about why we don't bother supporting it.
> >>
> >> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> >> ---
> >>  drivers/platform/x86/dell-rbtn.c | 15 +++++++++++++++
> >>  1 file changed, 15 insertions(+)
> >>
> >> diff --git a/drivers/platform/x86/dell-rbtn.c b/drivers/platform/x86/dell-rbtn.c
> >> index cd410e392550..b51a2008d782 100644
> >> --- a/drivers/platform/x86/dell-rbtn.c
> >> +++ b/drivers/platform/x86/dell-rbtn.c
> >> @@ -217,6 +217,21 @@ static void rbtn_notify(struct acpi_device *device, u32 event);
> >>  static const struct acpi_device_id rbtn_ids[] = {
> >>  	{ "DELRBTN", 0 },
> >>  	{ "DELLABCE", 0 },
> >> +
> >> +	/*
> >> +	 * This driver can also handle the "DELLABC6" device that
> >> +	 * appears on the XPS 13 9350, but that device is disabled
> >> +	 * by the DSDT unless booted with acpi_osi="!Windows 2012"
> >> +	 * acpi_osi="!Windows 2013".  Even if we boot that and bind
> >> +	 * the driver, we seem to have inconsistent behavior in
> >> +	 * which NetworkManager can get out of sync with the rfkill
> >> +	 * state.
> > Do you know reason for such behaviour? It is because event is send
> > duplicated (by dell-rbtn and also by intel-hid)?
> DELLABC6 is a custom interface that was created solely to have airplane
> mode support for Windows 7. 
> For Windows 10 the proper interface is to use that which is handled by
> intel-hid.  A OEM airplane mode driver is not used.
> 
> Since the kernel doesn't identify as Windows 7 it would be incorrect to
> do attempt to use that interface.

Ok, I understand. But what user can is to tell linux kernel to identify
as Windows 7.

And I would like to know reason for that inconsistent behaviour. It is
because of bug in NetworkManager or because of some hidden bug in
dell-rbnt.c or in rfkill kernel subsystem? If it is in kernel there is
really big change that it can occur also on other machines which uses
dell-rbtn and so we should fix it.

Andy, can you look at it and try identify where is the problem?

> >> +	 * On the XPS 13 9350 and similar laptops, we're not supposed to
> >> +	 * use DELLABC6 at all.  Instead, we handle the rfkill button
> >> +	 * via the intel-hid driver.
> >> +	 */
> >> +
> >>  	{ "", 0 },
> >>  };
> >>  
> 

-- 
Pali Rohár
pali.rohar@gmail.com