linux-kernel - RE: [PATCH 02/19] dt-bindings: serial: rsci: Drop "uart-has-rtscts: false"

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Message-ID:
 <TY3PR01MB113460F737A66E71E86482C5286FDA@TY3PR01MB11346.jpnprd01.prod.outlook.com>
Date: Tue, 28 Oct 2025 19:39:41 +0000
From: Biju Das <biju.das.jz@...renesas.com>
To: Conor Dooley <conor@...nel.org>
CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby
	<jirislaby@...nel.org>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski
	<krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Geert Uytterhoeven
	<geert+renesas@...der.be>, magnus.damm <magnus.damm@...il.com>, Prabhakar
 Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
	biju.das.au <biju.das.au@...il.com>
Subject: RE: [PATCH 02/19] dt-bindings: serial: rsci: Drop "uart-has-rtscts:
 false"

Hi Conor Dooley,

> -----Original Message-----
> From: Conor Dooley <conor@...nel.org>
> Sent: 28 October 2025 19:28
> Subject: Re: [PATCH 02/19] dt-bindings: serial: rsci: Drop "uart-has-rtscts: false"
> 
> On Mon, Oct 27, 2025 at 03:45:49PM +0000, Biju Das wrote:
> > Drop "uart-has-rtscts: false" from binding as the IP support hardware
> > flow control.
> 
> Why is it being removed, rather than only being required for the existing devices? It's not clear to
> me that the comment about the IP supporting flow control excludes the integration on these particular
> devices from somehow having flow control disabled.

It was a mistake previously as the driver does not implement hardware flow control and
is excluded in device tree.

Actually, the RSCI IP on all SoCs supports hardware flow control.
If a channel need flow control it can make use of the property uart-has-rtscts;
That is the reason for removing hardware flow control disabled property("uart-has-rtscts: false")


Cheers,
Biju



> 
> >
> > Signed-off-by: Biju Das <biju.das.jz@...renesas.com>
> > ---
> >  Documentation/devicetree/bindings/serial/renesas,rsci.yaml | 2 --
> >  1 file changed, 2 deletions(-)
> >
> > diff --git
> > a/Documentation/devicetree/bindings/serial/renesas,rsci.yaml
> > b/Documentation/devicetree/bindings/serial/renesas,rsci.yaml
> > index f50d8e02f476..6b1f827a335b 100644
> > --- a/Documentation/devicetree/bindings/serial/renesas,rsci.yaml
> > +++ b/Documentation/devicetree/bindings/serial/renesas,rsci.yaml
> > @@ -54,8 +54,6 @@ properties:
> >    power-domains:
> >      maxItems: 1
> >
> > -  uart-has-rtscts: false
> > -
> >  required:
> >    - compatible
> >    - reg
> > --
> > 2.43.0
> >