Date: Thu, 23 Jan 2014 16:53:50 +0000
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Lothar =?iso-8859-1?Q?Wa=DFmann?= <LW@KARO-electronics.de>,
        Mark Rutland <mark.rutland@arm.com>, linux-pwm@vger.kernel.org,
        Pawel Moll <pawel.moll@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        linux-kernel@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
        Thierry Reding <thierry.reding@gmail.com>,
        Rob Landley <rob@landley.net>, Kumar Gala <galak@codeaurora.org>,
        Shawn Guo <shawn.guo@linaro.org>, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/2] PWM: let of_xlate handlers check args count
Message-ID: <20140123165349.GY15937@n2100.arm.linux.org.uk>
References: <20140123083714.3c6e86ae@ipc1.ka-ro> <1390467898-9216-1-git-send-email-s.hauer@pengutronix.de> <1390467898-9216-2-git-send-email-s.hauer@pengutronix.de> <20140123115632.6d3f1a58@ipc1.ka-ro> <20140123110444.GI16215@pengutronix.de>
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On Thu, Jan 23, 2014 at 12:04:44PM +0100, Sascha Hauer wrote:
> On Thu, Jan 23, 2014 at 11:56:32AM +0100, Lothar Wa?mann wrote:
> > Hi,
> > 
> > Sascha Hauer wrote:
> > > of_pwm_n_cells for the of_xlate handler is stored in struct pwm_chip,
> > > but it is only ever used by the of_xlate handler itsel. Remove
> > > of_pwm_n_cells from struct pwm_chip and let the handler do the argument
> > > count checking to simplify the code.
> > > 
> > This still does not make the PWM_POLARITY flag in the pwms node
> > optional as was the goal because of_parse_phandle_with_args() requires
> > at least #pwm-cells arguments in the node.
> > 
> > So, with a DT configuration like:
> > pwm0: pwm@0 {
> > 	#pwm-cells = <3>;
> > };
> > backlight {
> > 	pwms = <&pwm0 0 100000>;
> > };
> 
> We misunderstood each other. My goal was to allow the driver to also
> work with old devicetrees which specify #pwm-cells = <2>, not to allow
> inconsistent devicetrees like the snippet above.

In which case, the patch I've posted seems to do that job too... I'm
just about to test out the three-cell version.

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