From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756127AbdE0LBR (ORCPT ); Sat, 27 May 2017 07:01:17 -0400 Received: from mail-wr0-f194.google.com ([209.85.128.194]:33059 "EHLO mail-wr0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752602AbdE0LBO (ORCPT ); Sat, 27 May 2017 07:01:14 -0400 From: Pali =?utf-8?q?Roh=C3=A1r?= To: Darren Hart Subject: Re: [PATCH] platform/x86: dell-rbtn: Improve explanation about DELLABC6 Date: Sat, 27 May 2017 13:01:10 +0200 User-Agent: KMail/1.13.7 (Linux/3.13.0-117-generic; KDE/4.14.2; x86_64; ; ) Cc: platform-driver-x86@vger.kernel.org, LKML , Andy Lutomirski , Mario Limonciello References: In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart115076582.QaZgfroqLs"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Message-Id: <201705271301.10526@pali> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --nextPart115076582.QaZgfroqLs Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Saturday 27 May 2017 07:16:19 Darren Hart wrote: > From: Andy Lutomirski >=20 > According to Mario at Dell, the DELLABC6 device should not be used on > a Linux system. It also conflicts with Intel-HID and its > interactions with Network Manager. Document that we are aware of the > device, but that we are intentionally ignoring it. >=20 > Signed-off-by: Andy Lutomirski > [dvhart: New commit message and minor comment wording fixes] > Cc: Mario Limonciello > Cc: "Pali Roh=C3=A1r" > Signed-off-by: Darren Hart (VMware) > --- > drivers/platform/x86/dell-rbtn.c | 26 +++++++++++++++++++------- > 1 file changed, 19 insertions(+), 7 deletions(-) >=20 > diff --git a/drivers/platform/x86/dell-rbtn.c > b/drivers/platform/x86/dell-rbtn.c index dcd9f40..2eeef03 100644 > --- a/drivers/platform/x86/dell-rbtn.c > +++ b/drivers/platform/x86/dell-rbtn.c > @@ -223,14 +223,26 @@ static const struct acpi_device_id rbtn_ids[] =3D > { * 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=3D"!Windows 2012" > - * acpi_osi=3D"!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. > + * acpi_osi=3D"!Windows 2013". > * > - * 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. > + * According to Mario at Dell: > + * > + * 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. > + * > + * Even if we override _OSI and bind to DELLABC6, we end up > + * with inconsistent behavior in which NetworkManager can get > + * out of sync with the rfkill state. This happens because > + * NetworkManager receives events from intel-hid and fights with > + * dell-rbtn for control. > + * > + * The upshot is that it's better to just ignore DELLABC6 > + * devices. > */ >=20 > { "", 0 }, Just one note: Kernel code should not depend on one particular software=20 which implements networking (in userspace). Either behaviour is=20 independent of used software and therefore comment does not apply only=20 to Network Manager OR behaviour is strictly bounded to Network Manager=20 which is IMHO not a kernel bug, but rather userspace software=20 application bug. If there is a bug in userspace, then userspace should=20 be fixed instead of adding hacks/workarounds in kernel. Currently from comment it is hard for non platform/x86/dell people to=20 decide if problem is in userspace or kernel/acpi. It could be understood=20 as two kernel drivers "dell-rbtn" and "intel-hid" are fighting, but also=20 as one particular software (network manager) is unable to handle state=20 with more then on driver. =2D-=20 Pali Roh=C3=A1r pali.rohar@gmail.com --nextPart115076582.QaZgfroqLs Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEYEABECAAYFAlkpXHYACgkQi/DJPQPkQ1JZyACffD/WV82EP56/ltLlJoui5PPe wZ0An0cAgmLhGUgeg2LtEUaRVPaRK5g0 =ixBw -----END PGP SIGNATURE----- --nextPart115076582.QaZgfroqLs--