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Message-ID: <ea3ee738155af7a0f19c2fef3a482a7d@vanmierlo.com>
Date: Sat, 28 Oct 2023 12:59:28 +0200
From: m.brock@...mierlo.com
To: Manikanta Guntupalli <manikanta.guntupalli@....com>
Cc: git@....com, michal.simek@....com, gregkh@...uxfoundation.org,
robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
conor+dt@...nel.org, linux-serial@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
jirislaby@...nel.org, linux-arm-kernel@...ts.infradead.org,
radhey.shyam.pandey@....com, srinivas.goud@....com,
shubhrajyoti.datta@....com, manion05gk@...il.com
Subject: Re: [PATCH V3 1/2] dt-bindings: Add optional gpio property to uartps
node to support rs485
Manikanta Guntupalli schreef op 2023-10-24 16:48:
> Add optional gpio property to uartps node and reference to rs485.yaml
>
> On Xilinx/AMD Kria SOM KD240 board rs485 connects via TI ISOW1432
> Transceiver device, where one GPIO is used for driving DE/RE signals.
> With rs485 half duplex configuration, DE and RE are shorted to each
> other,
> and at a time, any node acts as either a driver or a receiver.
>
> Here,
> DE - Driver enable. If pin is floating, driver is disabled.
> RE - Receiver enable. If pin is floating, receiver buffer is disabled.
>
> For more deatils, please find below link which contains Transceiver
> device(ISOW1432) datasheet
> https://www.ti.com/lit/ds/symlink/isow1432.pdf?ts=1682607122706&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FISOW1432%252Fpart-details%252FISOW1432DFMR%253FkeyMatch%253DISOW1432DFMR%2526tisearch%253Dsearch-everything%2526usecase%253DOPN
>
> rts-gpios is optional property, because it is not required
> for uart console node.
>
> Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@....com>
> ---
> Changes for V2:
> Modify optional gpio name to xlnx,phy-ctrl-gpios.
> Update commit description.
> Changes for V3:
> Modify optional gpio name to rts-gpios.
> Update commit description.
> ---
> Documentation/devicetree/bindings/serial/cdns,uart.yaml | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/serial/cdns,uart.yaml
> b/Documentation/devicetree/bindings/serial/cdns,uart.yaml
> index e35ad1109efc..7ee305f9a45f 100644
> --- a/Documentation/devicetree/bindings/serial/cdns,uart.yaml
> +++ b/Documentation/devicetree/bindings/serial/cdns,uart.yaml
> @@ -46,6 +46,11 @@ properties:
> power-domains:
> maxItems: 1
>
> + rts-gpios:
> + description: Optional GPIO to control transmit/receive on RS485
> phy
> + in halfduplex mode.
> + maxItems: 1
> +
Why would this be related to RS485? A user could also have a need for a
gpio instead of the native pin to be used as normal rts.
All RS485 references can be removed.
> required:
> - compatible
> - reg
> @@ -55,6 +60,7 @@ required:
>
> allOf:
> - $ref: serial.yaml#
> + - $ref: rs485.yaml#
> - if:
> properties:
> compatible:
Maarten
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