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Date:   Tue, 24 Oct 2023 08:33:34 -0500
From:   Rob Herring <robh@kernel.org>
To:     Brenda Streiff <brenda.streiff@ni.com>
Cc:     Gratian Crisan <gratian.crisan@ni.com>,
        Jason Smith <jason.smith@ni.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org
Subject: Re: [PATCH v6 tty-next 1/2] dt-bindings: serial: ni,ni16650: add
 bindings
Message-ID: <20231024133334.GA3505191-robh@kernel.org>
References: <20231023210458.447779-1-brenda.streiff@ni.com>
 <20231023210458.447779-2-brenda.streiff@ni.com>
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On Mon, Oct 23, 2023 at 04:04:56PM -0500, Brenda Streiff wrote:
> Add bindings for the NI 16550 UART.
> 
> Signed-off-by: Brenda Streiff <brenda.streiff@ni.com>
> Cc: Gratian Crisan <gratian.crisan@ni.com>
> Cc: Jason Smith <jason.smith@ni.com>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> ---
>  .../bindings/serial/ni,ni16550.yaml           | 51 +++++++++++++++++++
>  1 file changed, 51 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/serial/ni,ni16550.yaml
> 
> diff --git a/Documentation/devicetree/bindings/serial/ni,ni16550.yaml b/Documentation/devicetree/bindings/serial/ni,ni16550.yaml
> new file mode 100644
> index 000000000000..72ab125dd892
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/serial/ni,ni16550.yaml
> @@ -0,0 +1,51 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/serial/ni,ni16550.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: NI 16550 asynchronous serial interface (UART)

Is this significantly different than all the other 8250 compatible UARTs 
in 8250.yaml?

> +
> +maintainers:
> +  - Brenda Streiff <brenda.streiff@ni.com>
> +
> +allOf:
> +  - $ref: serial.yaml#
> +
> +properties:
> +  compatible:
> +    const: ni,ni16550
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 1
> +
> +  ni,serial-port-mode:
> +    description: Indicates whether this is an RS-232 or RS-485 serial port.
> +    $ref: /schemas/types.yaml#/definitions/string
> +    enum: [ RS-232, RS-485 ]
> +    default: RS-485

We already have 'linux,rs485-enabled-at-boot-time' which seems similar 
purpose. It also tells me this is not a fixed in hardware setting. If 
that property doesn't work for you, come up with something common and 
explain why. Or explain why this is completely unique to this UART.

Rob