From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759940AbcAUQ2V (ORCPT ); Thu, 21 Jan 2016 11:28:21 -0500 Received: from mezzanine.sirena.org.uk ([106.187.55.193]:38700 "EHLO mezzanine.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759903AbcAUQ2Q (ORCPT ); Thu, 21 Jan 2016 11:28:16 -0500 Date: Thu, 21 Jan 2016 16:26:46 +0000 From: Mark Brown To: Lothar =?iso-8859-1?Q?Wa=DFmann?= Cc: =?iso-8859-1?Q?Beno=EEt?= Cousson , Ian Campbell , Kumar Gala , Liam Girdwood , Mark Rutland , Pawel Moll , Rob Herring , Russell King , Tony Lindgren , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org Message-ID: <20160121162646.GK6588@sirena.org.uk> References: <1453292992-1788-1-git-send-email-LW@KARO-electronics.de> <1453292992-1788-2-git-send-email-LW@KARO-electronics.de> <20160120164258.GF6588@sirena.org.uk> <20160121080524.27af489f@ipc1.ka-ro> <20160121102015.GI6588@sirena.org.uk> <20160121112611.34e17cb2@ipc1.ka-ro> <20160121111115.GJ6588@sirena.org.uk> <20160121123311.5346e40d@ipc1.ka-ro> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="eJpN0D5W9Nffl1c7" Content-Disposition: inline In-Reply-To: <20160121123311.5346e40d@ipc1.ka-ro> X-Cookie: APL hackers do it in the quad. User-Agent: Mutt/1.5.24 (2015-08-30) X-SA-Exim-Connect-IP: 2a01:348:6:8808:fab::3 X-SA-Exim-Mail-From: broonie@sirena.org.uk Subject: Re: [PATCH 1/2] regulator: ltc3589: make IRQ optional X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:24:06 +0000) X-SA-Exim-Scanned: Yes (on mezzanine.sirena.org.uk) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --eJpN0D5W9Nffl1c7 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jan 21, 2016 at 12:33:11PM +0100, Lothar Wa=DFmann wrote: > > On Thu, Jan 21, 2016 at 11:26:11AM +0100, Lothar Wa=DFmann wrote: > > > > On Thu, Jan 21, 2016 at 08:05:24AM +0100, Lothar Wa=DFmann wrote: > > > > > > On Wed, Jan 20, 2016 at 01:29:51PM +0100, Lothar Wa=DFmann wrot= e: > > > > > > > This pin is used as IRQ pin for the LTC3589 PMIC on the Ka-Ro > > > > > > > electronics TX48 module. Make the IRQ optional in the driver = and use a > > > > > > > polling routine instead if no IRQ is specified in DT. > > > > > > > Otherwise the driver will continuously generate interrupts an= d make > > > > > > > the system unusable. > It won't. That's the whole purpose of this patch. > I'm afraid, I don't quite understand what you want to say... Your commit message (quoted above) claims that without this patch if no interrupt is supplied then the unsupplied interrupt will somehow be left screaming and make the system unusable. This doesn't make sense, if there is no interrupt there is nothing to scream. > Without this patch there will be a constantly active interrupt, which > will stall the system because the nNMI interrupt (on the EXTINTn pin) is > level triggered. > Since the polarity of the interrupt input is fixed, there is no way to > use it in our HW. So, contrary to what you've been saying, the interrupt is actually connected (and worse, connected to a NMI) but apparently not described in DT. Why is it sensible to make the driver poll (which will affect all systems using this device, even those that don't care) and not just describe the interrupt in DT so it can be handled promptly in the normal fashion? Presumably this will run into serious problems if the interrupt actually fires at runtime since the NMI will scream, it's not clear to me how the poll will manage to run successfully in that case. This really feels like a very system specific workaround which is attempting to address things in the wrong place and coming up with something very non-obvious as a result. --eJpN0D5W9Nffl1c7 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJWoQbFAAoJECTWi3JdVIfQQQUH/Amafmd4EIoMHLytpYVzneH9 pk6d9qXm/PVEzN3tUpWNvO88Inu2itimAl/VADnwlQJlH5yQKWGpXIe33DrsAxCN 7A1gKmH6bNWttCEUzDH1mYVDEmkiE5bb5iOUHXwaj/RVgBwt4ZMfcBg/pfaI63CZ F/VP/TKS5yZpyf8HvM1dN30zMl8S6eSAlzxehhi/oCMb5z7l9t6J4H1XA0ftIpO7 JOsmPhqcgypCSQQz7IQKFyy9IfcUkNuc+DZOLFX9Q7yuJreOdo8STkcZERtc5wSK N6fGD5rEtcatU+YNilOJ720GiOFsW4rL5dtIgJyQfZAr5hYgyWNji1SGhp1YSnY= =3Q/K -----END PGP SIGNATURE----- --eJpN0D5W9Nffl1c7--