Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Sat, 27 Jul 2019 11:01:54 +0300
From:   Dmitry Torokhov <dmitry.torokhov@gmail.com>
To:     Rob Herring <robh@kernel.org>
Cc:     Michal =?utf-8?B?Vm9rw6HEjQ==?= <michal.vokac@ysoft.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        linux-input@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Pengutronix Kernel Team <kernel@pengutronix.de>
Subject: Re: [RFC PATCH v2 1/4] dt-bindings: input: Add support for the
 MPR121 without interrupt line
Message-ID: <20190727080154.GB795@penguin>
References: <1558098773-47416-1-git-send-email-michal.vokac@ysoft.com>
 <1558098773-47416-2-git-send-email-michal.vokac@ysoft.com>
 <20190613223945.GA938@bogus>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20190613223945.GA938@bogus>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, Jun 13, 2019 at 04:39:45PM -0600, Rob Herring wrote:
> On Fri, May 17, 2019 at 03:12:50PM +0200, Michal Vokáč wrote:
> > Normally, the MPR121 controller uses separate interrupt line to notify
> > the I2C host that a key was touched/released. To support platforms that
> > can not use the interrupt line, polling of the MPR121 registers can be
> > used.
> 
> 'separate' from what?
> 
> > 
> > Signed-off-by: Michal Vokáč <michal.vokac@ysoft.com>
> > ---
> > Changes since v1:
> > - Document the polled binding in the original file, do not create a new one.
> >   (Rob)
> > 
> >  Documentation/devicetree/bindings/input/mpr121-touchkey.txt | 9 +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/input/mpr121-touchkey.txt b/Documentation/devicetree/bindings/input/mpr121-touchkey.txt
> > index b7c61ee5841b..97f55273d473 100644
> > --- a/Documentation/devicetree/bindings/input/mpr121-touchkey.txt
> > +++ b/Documentation/devicetree/bindings/input/mpr121-touchkey.txt
> > @@ -1,9 +1,14 @@
> > -* Freescale MPR121 Controllor
> > +* Freescale MPR121 Controller
> >  
> >  Required Properties:
> > -- compatible:		Should be "fsl,mpr121-touchkey"
> > +- compatible:		Should be one of:
> > +			- "fsl,mpr121-touchkey" - MPR121 with interrupt line
> > +			- "fsl,mpr121-touchkey-polled" - MPR121 with polling
> >  - reg:			The I2C slave address of the device.
> >  - interrupts:		The interrupt number to the cpu.
> > +			In case of "fsl,mpr121-touchkey-polled" the interrupt
> > +			line is not used and hence the interrupts property is
> > +			not required.
> 
> Absence of the interrupts property is enough to determine polled mode 
> and you don't need a separate compatible string.

I would prefer if we could distinguish between chip working in polled
mode intentionally vs DT writer simply forgetting to specify interrupt
property. Should we key the polling mode off "linux,poll-interval"
property? We probably going to need it anyway as not everyone needs the
same polling frequency.

Thanks.

-- 
Dmitry