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SubjectRe: [PATCH 2/2] dt-bindings: iio: imu: adis16480: Document external clock
On Thu, 7 Mar 2019 17:29:19 +0200
Stefan Popa <stefan.popa@analog.com> wrote:

> Add documentation for optional use of external clock. All devices
> supported by this driver can work with an external clock in sync mode.
> Another mode, called Pulse Per Second (PPS) is supported only by adis1649x
> devices. The mode is selected by using the "clock-names" property.
>
> The pin which is used as external clock input is selected by using a
> custom optional property called "adi,ext-clk-pin". If this field is left
> empty, DIO2 is assigned as default external clock input pin.
>
> Signed-off-by: Stefan Popa <stefan.popa@analog.com>
Trivial comments inline...

Thanks,

Jonathan

> ---
> .../devicetree/bindings/iio/imu/adi,adis16480.txt | 34 ++++++++++++++++++++++
> 1 file changed, 34 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/iio/imu/adi,adis16480.txt b/Documentation/devicetree/bindings/iio/imu/adi,adis16480.txt
> index 39ab016..9e2fcd4 100644
> --- a/Documentation/devicetree/bindings/iio/imu/adi,adis16480.txt
> +++ b/Documentation/devicetree/bindings/iio/imu/adi,adis16480.txt
> @@ -34,6 +34,37 @@ Optional properties:
> signal.
> - reset-gpios: must be the device tree identifier of the RESET pin. As the line
> is active low, it should be marked GPIO_ACTIVE_LOW.
> +- clocks: phandle to the external clock. Should be set according to
> + "clock-names".
> + If this field is left empty, the internal clock is used.
> +- clock-names: The name of the external clock to be used. Valid values are:
> + * sync: In sync mode, the internal clock is disabled and the frequency
> + of the external clock signal establishes therate of data
the rate
> + collection and processing. See Fig 14 and 15 in the datasheet.
> + The clock-frequency must be:
> + * 3000 to 4500 Hz for adis1649x devices.
> + * 700 to 2400 Hz for adis1648x devices.
> + * pps: In Pulse Per Second (PPS) Mode, the rate of data collection and
> + production is equal to the product of the external clock
> + frequency and the scale factor in the SYNC_SCALE register, see
> + Table 154 in the datasheet.
> + The clock-frequency must be:
> + * 1 to 128 Hz for adis1649x devices.
> + * This mode is not supported by adis1648x devices.
> + If this field is left empty, the internal clock is used.

Should we say that both clocks and clock-names should be empty if that is
the intent?

> +- adi,ext-clk-pin: The DIOx line to be used as an external clock input.
> + Valid values are:
> + * DIO1
> + * DIO2
> + * DIO3
> + * DIO4
> + Each DIOx pin supports only one function at a time (data ready line
> + selection or external clock input). When a single pin has two
> + two assignments, the enable bit for the lower priority function
> + automatically resets to zero (disabling the lower priority function).
> + Data ready has highest priority.
> + If this field is left empty, DIO2 is assigned as default external clock
> + input pin.
>
> Example:
>
> @@ -46,4 +77,7 @@ Example:
> interrupts = <25 IRQF_TRIGGER_FALLING>;
> interrupt-parent = <&gpio>;
> interrupt-names = "DIO2";
> + clocks = <&adis16495_sync>;
> + clock-names = "sync";
> + adi,ext-clk-pin = "DIO1";
> };


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