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Subject: Re: [PATCH v2 02/16] pwm: pxa: update documentation regarding
 pwm-cells
To:     Rob Herring <robh@kernel.org>
CC:     <thierry.reding@gmail.com>, <mark.rutland@arm.com>,
        <linux@armlinux.org.uk>, <daniel@zonque.org>,
        <haojian.zhuang@gmail.com>, <robert.jarzmik@free.fr>,
        <corbet@lwn.net>, <nicolas.ferre@microchip.com>,
        <alexandre.belloni@free-electrons.com>,
        <linux-pwm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-amlogic@lists.infradead.org>,
        <linux-rockchip@lists.infradead.org>,
        <linux-rpi-kernel@lists.infradead.org>,
        <devicetree@vger.kernel.org>, Mike Dunn <mikedunn@newsguy.com>
References: <1515766983-15151-1-git-send-email-claudiu.beznea@microchip.com>
 <1515766983-15151-3-git-send-email-claudiu.beznea@microchip.com>
 <20180119223024.m5kuc6467xmgkgac@rob-hp-laptop>
From:   Claudiu Beznea <Claudiu.Beznea@microchip.com>
Message-ID: <6889fdc0-6d61-830e-dad5-2efc02b1b277@microchip.com>
Date:   Mon, 22 Jan 2018 10:47:13 +0200
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On 20.01.2018 00:30, Rob Herring wrote:
> On Fri, Jan 12, 2018 at 04:22:49PM +0200, Claudiu Beznea wrote:
>> pwm-cells should be at least 2 to provide channel number and period value.
>>
>> Cc: Mike Dunn <mikedunn@newsguy.com>
>> Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
>> ---
>>  Documentation/devicetree/bindings/pwm/pxa-pwm.txt | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/pwm/pxa-pwm.txt b/Documentation/devicetree/bindings/pwm/pxa-pwm.txt
>> index 5ae9f1e3c338..a0e20edeeebc 100644
>> --- a/Documentation/devicetree/bindings/pwm/pxa-pwm.txt
>> +++ b/Documentation/devicetree/bindings/pwm/pxa-pwm.txt
>> @@ -10,7 +10,7 @@ Required properties:
>>    Note that one device instance must be created for each PWM that is used, so the
>>    length covers only the register window for one PWM output, not that of the
>>    entire PWM controller.  Currently length is 0x10 for all supported devices.
>> -- #pwm-cells: Should be 1.  This cell is used to specify the period in
>> +- #pwm-cells: Should be 2.  This cell is used to specify the period in
>>    nanoseconds.
> 
> What's the new cell? channel? Does the PXA PWM have more than one 
> channel? If not, then you shouldn't add a cell.
The new cell had to be period, to have a generic OF function in the kernel,
to parse the pwms bindings for all PWMs, something like
pwms=<pwm channel-number pwm-period>. After several discussions on this
series, I found that old DT binaries must be compatible with latest kernel
version and this series doesn't guarantee this. So I will drop this change
in next version.

Thank you,
Claudiu Beznea
> 
> Rob
>