Hi Rob Herring, > -----Original Message----- > From: Rob Herring <robh@xxxxxxxxxx> > Sent: Thursday, April 27, 2023 10:14 PM > To: Guntupalli, Manikanta <manikanta.guntupalli@xxxxxxx> > Cc: gregkh@xxxxxxxxxxxxxxxxxxx; krzysztof.kozlowski+dt@xxxxxxxxxx; > michal.simek@xxxxxxxxxx; linux-serial@xxxxxxxxxxxxxxx; > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > jirislaby@xxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; Simek, Michal > <michal.simek@xxxxxxx>; git (AMD-Xilinx) <git@xxxxxxx>; Pandey, > Radhey Shyam <radhey.shyam.pandey@xxxxxxx>; Datta, Shubhrajyoti > <shubhrajyoti.datta@xxxxxxx>; Goud, Srinivas <srinivas.goud@xxxxxxx>; > manion05gk@xxxxxxxxx > Subject: Re: [PATCH 1/2] dt-bindings: Add optional gpio property to uartps > node to support rs485 > > On Wed, Apr 26, 2023 at 05:59:46PM +0530, Manikanta Guntupalli wrote: > > Add optional gpio property to uartps node and add reference to rs485.yaml > > The diff tells me that already. Why? Please check Figure 11-3 (Page number 37) in the below mentioned data sheet, It shows PMOD (ISOW14x2) devices used in half duplex configuration. Driver outputs Y and Z are shorted to A and B respectively. This reduces overall cabling requirements. Also DE/RE are shorted to each other, and at a time, any node acts as either a driver or a receiver. Using above optional GPIO controlling driver or a receiver. This GPIO is optional because it is not required for uart console node. Here, DE - Driver enable. If pin is floating, driver is disabled (internal pull-down resistor) RE - Receiver enable. If pin is floating, receiver buffer is disabled (internal pull-up resistor) 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 > > > > > Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@xxxxxxx> > > --- > > Documentation/devicetree/bindings/serial/cdns,uart.yaml | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/serial/cdns,uart.yaml > b/Documentation/devicetree/bindings/serial/cdns,uart.yaml > > index a8b323d7bf94..34ed0d80b923 100644 > > --- a/Documentation/devicetree/bindings/serial/cdns,uart.yaml > > +++ b/Documentation/devicetree/bindings/serial/cdns,uart.yaml > > @@ -46,6 +46,10 @@ properties: > > power-domains: > > maxItems: 1 > > > > + txrx-gpios: > > + description: Optional GPIO to switch transmit and receive modes via > pmod. > > What's pmod? Pmod is galvanically-isolated RS-485/RS-422 transceivers with a built-in isolated DC-DC converter, that eliminates the need for a separate isolated power supply in space constrained isolated designs. > > > + maxItems: 1 > > + > > required: > > - compatible > > - reg > > @@ -55,6 +59,7 @@ required: > > > > allOf: > > - $ref: serial.yaml# > > + - $ref: rs485.yaml# > > - if: > > properties: > > compatible: > > -- > > 2.25.1 > >
