From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lothar =?UTF-8?B?V2HDn21hbm4=?= Subject: Re: [PATCH 1/2] regulator: ltc3589: make IRQ optional Date: Thu, 21 Jan 2016 12:33:11 +0100 Message-ID: <20160121123311.5346e40d@ipc1.ka-ro> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20160121111115.GJ6588-GFdadSzt00ze9xe1eoZjHA@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mark Brown Cc: =?UTF-8?B?QmVub8OudA==?= Cousson , Ian Campbell , Kumar Gala , Liam Girdwood , Mark Rutland , Pawel Moll , Rob Herring , Russell King , Tony Lindgren , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org Hi, > On Thu, Jan 21, 2016 at 11:26:11AM +0100, Lothar Wa=C3=9Fmann wrote: > > > On Thu, Jan 21, 2016 at 08:05:24AM +0100, Lothar Wa=C3=9Fmann wro= te: > > > > > On Wed, Jan 20, 2016 at 01:29:51PM +0100, Lothar Wa=C3=9Fmann= wrote: >=20 > > > > > > This pin is used as IRQ pin for the LTC3589 PMIC on the Ka-= Ro > > > > > > electronics TX48 module. Make the IRQ optional in the drive= r and use a > > > > > > polling routine instead if no IRQ is specified in DT. > > > > > > Otherwise the driver will continuously generate interrupts = and make > > > > > > the system unusable. >=20 > > > > > How will the driver generate interrupts if there is no interr= upt > > > > > physically present in the system? >=20 > > > > It's using timer interrupts to poll the LTC3589 state. >=20 > > > I know that is what your patch does, my question is why you say i= n your > > > commit log that "Otherwise the driver will continuously generate > > > interrupts and make the system unusable". >=20 > > Because the interrupt is level triggered and the polarity of the > > EXTINT pin is inverted, the interrupt will be constantly active whe= n > > the IRQ pin of the LTC3589 is inactive. >=20 > So, to repeat my original question, how will that generate interrupts= if > there is no interrupt physically present in the system? > It won't. That's the whole purpose of this patch. I'm afraid, I don't quite understand what you want to say... Without this patch there will be a constantly active interrupt, which will stall the system because the nNMI interrupt (on the EXTINTn pin) i= s level triggered. Since the polarity of the interrupt input is fixed, there is no way to use it in our HW. Lothar Wa=C3=9Fmann -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html