linux-kernel - Re: [PATCH v5 01/17] dt-bindings: serial: renesas,rsci: Document RZ/G3E support

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Message-ID: <20251209190254.GA927812-robh@kernel.org>
Date: Tue, 9 Dec 2025 13:02:54 -0600
From: Rob Herring <robh@...nel.org>
To: Biju Das <biju.das.jz@...renesas.com>
Cc: Krzysztof Kozlowski <krzk@...nel.org>,
	"biju.das.au" <biju.das.au@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...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>,
	wsa+renesas <wsa+renesas@...g-engineering.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>
Subject: Re: [PATCH v5 01/17] dt-bindings: serial: renesas,rsci: Document
 RZ/G3E support

On Thu, Dec 04, 2025 at 08:23:06AM +0000, Biju Das wrote:
> Hi Krzysztof Kozlowski,
> 
> Thanks for the feedback.
> 
> > -----Original Message-----
> > From: Krzysztof Kozlowski <krzk@...nel.org>
> > Sent: 04 December 2025 08:03
> > Subject: Re: [PATCH v5 01/17] dt-bindings: serial: renesas,rsci: Document RZ/G3E support
> > 
> > On Sat, Nov 29, 2025 at 04:42:57PM +0000, Biju wrote:
> > > From: Biju Das <biju.das.jz@...renesas.com>
> > >
> > > Add documentation for the serial communication interface (RSCI) found
> > > on the Renesas RZ/G3E (R9A09G047) SoC. The RSCI IP on this SoC is
> > > identical to that on the RZ/T2H (R9A09G077) SoC, but it has a 32-stage
> > > FIFO compared to 16 on RZ/T2H. It supports both FIFO and non-FIFO mode
> > > operation. RZ/G3E has 6 clocks(5 module clocks + 1 external clock)
> > > compared to 3 clocks
> > > (2 module clocks + 1 external clock) on RZ/T2H, and it has multiple resets.
> > > It has 6 interrupts compared to 4 on RZ/T2H.
> > >
> > > Signed-off-by: Biju Das <biju.das.jz@...renesas.com>
> > > ---
> > > v4->v5:
> > >  * Updated commit description related to IRQ difference
> > >  * Added aed and bfd irqs for RZ/G3E.
> > >  * Moved reset: false to RZ/T2H SoC and dropped the else part for RZ/G3E.
> > >  * Updated conditional schema with interrupts and interrupts-names.
> > >  * Dropped the tag as there are new changes.
> > > v3->v4:
> > >  * Dropped separate compatible for non-FIFO mode and instead using single
> > >    compatible "renesas,r9a09g047-rsci" as non-FIFO mode can be achieved
> > >    by software configuration.
> > >  * Renamed clock-names bus->pclk
> > >  * Rearranged clock-names tclk{4, 16, 64}
> > >  * Retained the tag as the changes are trivial.
> > > v2->v3:
> > >  * Dropped 1st and 3rd items from clk-names and added minItems for the
> > >    range.
> > >  * Added minItems for clk and clk-names for RZ/T2H as the range is 2-3
> > >  * Added maxItems for clk and clk-names for RZ/G3E as the range is 5-6
> > >  * Retained the tag as it is trivial change.
> > > v1->v2:
> > >  * Updated commit message
> > >  * Added resets:false for non RZ/G3E SoCs.
> > > ---
> > >  .../bindings/serial/renesas,rsci.yaml         | 99 ++++++++++++++++---
> > >  1 file changed, 88 insertions(+), 11 deletions(-)
> > >
> > > diff --git
> > > a/Documentation/devicetree/bindings/serial/renesas,rsci.yaml
> > > b/Documentation/devicetree/bindings/serial/renesas,rsci.yaml
> > > index 6b1f827a335b..1f8cee8171de 100644
> > > --- a/Documentation/devicetree/bindings/serial/renesas,rsci.yaml
> > > +++ b/Documentation/devicetree/bindings/serial/renesas,rsci.yaml
> > > @@ -10,46 +10,72 @@ maintainers:
> > >    - Geert Uytterhoeven <geert+renesas@...der.be>
> > >    - Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > >
> > > -allOf:
> > > -  - $ref: serial.yaml#
> > > -
> > >  properties:
> > >    compatible:
> > >      oneOf:
> > > -      - items:
> > > -          - const: renesas,r9a09g087-rsci # RZ/N2H
> > > -          - const: renesas,r9a09g077-rsci # RZ/T2H
> > > +      - enum:
> > > +          - renesas,r9a09g047-rsci # RZ/G3E
> > > +          - renesas,r9a09g077-rsci # RZ/T2H
> > >
> > >        - items:
> > > +          - const: renesas,r9a09g087-rsci # RZ/N2H
> > >            - const: renesas,r9a09g077-rsci # RZ/T2H
> > >
> > >    reg:
> > >      maxItems: 1
> > >
> > >    interrupts:
> > > +    minItems: 4
> > >      items:
> > >        - description: Error interrupt
> > >        - description: Receive buffer full interrupt
> > >        - description: Transmit buffer empty interrupt
> > >        - description: Transmit end interrupt
> > > +      - description: Active edge detection interrupt
> > > +      - description: Break field detection interrupt
> > >
> > >    interrupt-names:
> > > +    minItems: 4
> > >      items:
> > >        - const: eri
> > >        - const: rxi
> > >        - const: txi
> > >        - const: tei
> > > +      - const: aed
> > > +      - const: bfd
> > >
> > >    clocks:
> > >      minItems: 2
> > > -    maxItems: 3
> > > +    maxItems: 6
> > >
> > >    clock-names:
> > > -    minItems: 2
> > > +    oneOf:
> > > +      - items:
> > > +          - const: operation
> > > +          - const: bus
> > > +          - const: sck # optional external clock input
> > > +
> > > +        minItems: 2
> > > +
> > > +      - items:
> > > +          - const: pclk

Isn't this still just 'bus'?

> > > +          - const: tclk

And 'operation'?

Sure, renaming would look nicer, but better to extend than just change 
the binding.

> > > +          - const: tclk_div4
> > > +          - const: tclk_div16
> > > +          - const: tclk_div64
> > > +          - const: sck # optional external clock input
> > > +
> > > +        minItems: 5
> > > +
> > > +  resets:
> > >      items:
> > > -      - const: operation
> > > -      - const: bus
> > > -      - const: sck # optional external clock input
> > > +      - description: Input for resetting the APB clock
> > > +      - description: Input for resetting TCLK
> > > +
> > > +  reset-names:
> > > +    items:
> > > +      - const: presetn
> > > +      - const: tresetn
> > 
> > You did not include lore links, so I cannot check whether we already talked about this (why you still
> > do not send big patchsets like this with b4?), but you are mixing here devices with completely
> > different innputs. This does not make the binding readable.
> 
> See the links.
> 
> https://lore.kernel.org/all/20251031000012.GA466250-robh@kernel.org/
> 
> https://lore.kernel.org/linux-renesas-soc/20251030-regroup-garter-c70c7fc6a71a@spud/
> 
> I use the below command to send the patches, is it wrong? I will try b4 next time.
> 
> git send-email --annotate *.patch
> 
> > 
> > Split the binding.
> 
> I can split the binding, if Rob/Conor/Geert is OK with it.
> 
> Ie, Always put per SoC changes in new dt bindings files to make it more readable without any complex if
> statements.

There's no hard rule. It's a judgement call. If the if/then schemas are 
longer than the main schema, then it is probably time for a split. The 
downside to splitting is then there's no motivation to keep resource 
names the same (and makes it harder to review that).

Rob