linux-kernel - Re: [PATCH v6 6/9] dt-bindings: counter: Document stm32 quadrature encoder

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Message-ID: <20180518162815.GA24966@rob-hp-laptop>
Date:   Fri, 18 May 2018 11:28:15 -0500
From:   Rob Herring <robh@...nel.org>
To:     Benjamin Gaignard <benjamin.gaignard@...aro.org>
Cc:     William Breathitt Gray <vilhelm.gray@...il.com>,
        Mark Rutland <mark.rutland@....com>,
        devicetree@...r.kernel.org,
        Benjamin Gaignard <benjamin.gaignard@...com>,
        linux-iio@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        Fabrice Gasnier <fabrice.gasnier@...com>,
        Jonathan Cameron <jic23@...nel.org>
Subject: Re: [PATCH v6 6/9] dt-bindings: counter: Document stm32 quadrature
 encoder

On Thu, May 17, 2018 at 08:59:40PM +0200, Benjamin Gaignard wrote:
> 2018-05-17 18:23 GMT+02:00 Rob Herring <robh+dt@...nel.org>:
> > On Wed, May 16, 2018 at 12:51 PM, William Breathitt Gray
> > <vilhelm.gray@...il.com> wrote:
> >> From: Benjamin Gaignard <benjamin.gaignard@...com>
> >
> > v6? Where's v1-v5?
> >
> >> Add bindings for STM32 Timer quadrature encoder.
> >> It is a sub-node of STM32 Timer which implement the
> >> counter part of the hardware.
> >>
> >> Cc: Rob Herring <robh+dt@...nel.org>
> >> Cc: Mark Rutland <mark.rutland@....com>
> >> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...com>
> >> Signed-off-by: William Breathitt Gray <vilhelm.gray@...il.com>
> >> ---
> >>  .../bindings/counter/stm32-timer-cnt.txt      | 26 +++++++++++++++++++
> >>  .../devicetree/bindings/mfd/stm32-timers.txt  |  7 +++++
> >>  2 files changed, 33 insertions(+)
> >>  create mode 100644 Documentation/devicetree/bindings/counter/stm32-timer-cnt.txt
> >>
> >> diff --git a/Documentation/devicetree/bindings/counter/stm32-timer-cnt.txt b/Documentation/devicetree/bindings/counter/stm32-timer-cnt.txt
> >> new file mode 100644
> >> index 000000000000..377728128bef
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/counter/stm32-timer-cnt.txt
> >> @@ -0,0 +1,26 @@
> >> +STMicroelectronics STM32 Timer quadrature encoder
> >> +
> >> +STM32 Timer provides quadrature encoder counter mode to detect
> >
> > 'mode' does not sound like a sub-block of the timers block.
> 
> quadrature encoding is one of the counting modes of this hardware
> block which is enable to count on other signals/triggers

You don't need a child node and compatible to set a mode.

> >> +angular position and direction of rotary elements,
> >> +from IN1 and IN2 input signals.
> >> +
> >> +Must be a sub-node of an STM32 Timer device tree node.
> >> +See ../mfd/stm32-timers.txt for details about the parent node.
> >> +
> >> +Required properties:
> >> +- compatible:          Must be "st,stm32-timer-counter".
> >> +- pinctrl-names:       Set to "default".
> >> +- pinctrl-0:           List of phandles pointing to pin configuration nodes,
> >> +                       to set IN1/IN2 pins in mode of operation for Low-Power
> >> +                       Timer input on external pin.
> >> +
> >> +Example:
> >> +       timers@...10000  {
> >> +               compatible = "st,stm32-timers";
> >> +               ...
> >> +               counter {
> >> +                       compatible = "st,stm32-timer-counter";
> >
> > Is there only 1? How is the counter addressed?
> 
> Yes there is only one counter per hardware block.
> Counter is addressed like the two others sub-nodes and the details
> about parent mode are describe in stm32-timers.txt
> Should I add them here too ? so example will be like that:

No, you should drop the child node and add pinctrl to the parent.

Any other functions this block has that you plan on adding? Please make 
bindings as complete as possible, not what you currently have drivers 
for.

> timers@...10000  {
>   #address-cells = <1>;
>   #size-cells = <0>;
>   compatible = "st,stm32-timers";
>   reg = <0x40010000 0x400>;
>   clocks = <&rcc 0 160>;
>   clock-names = "int";
>   counter {
>     compatible = "st,stm32-timer-counter";
>     pinctrl-names = "default";
>     pinctrl-0 = <&tim1_in_pins>;
>     };
>  };
> 
> Benjamin
> >
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel@...ts.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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