linux-kernel - Re: [PATCH 02/16] dt-bindings: soc: renesas: renesas,rzg2l-sysc: Add #reset-cells for RZ/G3S

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Message-ID: <e0308678-c031-41e1-8d07-d2b78504180f@tuxon.dev>
Date: Fri, 23 Aug 2024 10:59:39 +0300
From: claudiu beznea <claudiu.beznea@...on.dev>
To: Conor Dooley <conor@...nel.org>
Cc: vkoul@...nel.org, kishon@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
 conor+dt@...nel.org, p.zabel@...gutronix.de, geert+renesas@...der.be,
 magnus.damm@...il.com, gregkh@...uxfoundation.org, mturquette@...libre.com,
 sboyd@...nel.org, yoshihiro.shimoda.uh@...esas.com,
 biju.das.jz@...renesas.com, ulf.hansson@...aro.org,
 linux-phy@...ts.infradead.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
 linux-usb@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-clk@...r.kernel.org, linux-pm@...r.kernel.org,
 Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH 02/16] dt-bindings: soc: renesas: renesas,rzg2l-sysc: Add
 #reset-cells for RZ/G3S



On 22.08.2024 19:44, Conor Dooley wrote:
> On Thu, Aug 22, 2024 at 05:42:57PM +0100, Conor Dooley wrote:
>> On Thu, Aug 22, 2024 at 06:27:47PM +0300, Claudiu wrote:
>>> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>>>
>>> The RZ/G3S System controller has registers to control signals that need
>>> to be de-asserted/asserted before/after different SoC areas are power
>>> on/off. This signals are implemented as reset signals. For this document
>>> the #reset-cells property.
>>>
>>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>>> ---
>>>  .../bindings/soc/renesas/renesas,rzg2l-sysc.yaml | 16 ++++++++++++++++
>>>  1 file changed, 16 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/soc/renesas/renesas,rzg2l-sysc.yaml b/Documentation/devicetree/bindings/soc/renesas/renesas,rzg2l-sysc.yaml
>>> index 4386b2c3fa4d..6b0bb34485d9 100644
>>> --- a/Documentation/devicetree/bindings/soc/renesas/renesas,rzg2l-sysc.yaml
>>> +++ b/Documentation/devicetree/bindings/soc/renesas/renesas,rzg2l-sysc.yaml
>>> @@ -42,12 +42,28 @@ properties:
>>>        - const: cm33stbyr_int
>>>        - const: ca55_deny
>>>  
>>> +  "#reset-cells":
>>> +    const: 1
>>> +
>>>  required:
>>>    - compatible
>>>    - reg
>>>  
>>>  additionalProperties: false
>>>  
>>> +allOf:
>>> +  - if:
>>> +      properties:
>>> +        compatible:
>>> +          contains:
>>> +            const: renesas,r9a08g045-sysc
>>> +    then:
>>> +      required:
>>> +        - "#reset-cells"
>>
>> Given this is new required property on an existing platform, I'd expect
>> some mention of why it used to be okay to not have this but is now
>> required. Did firmware or a bootloader stage take things out of reset?
> 
> Reading a bit more into the series, the peripherals in question were
> just never used nor did a driver for the sysc exist, so there's neither

Exactly.

> explanation of prior behaviour nor concerns about compatibility?

The newly introduced sysc driver is probed only for RZ/G3S and used to
control the USB, PCIe signals though reset control driver (registered by
sysc driver on auxiliary bus) and to identify the chip. The intention is to
later migrate the chip identification support for the rest of RZ/G2 devices
to this new driver and add more functionalities, when/if needed.

Thank you,
Claudiu Beznea

> 
>>
>>> +    else:
>>> +      properties:
>>> +        "#reset-cells": false
>>> +
>>>  examples:
>>>    - |
>>>      #include <dt-bindings/interrupt-controller/arm-gic.h>
>>> -- 
>>> 2.39.2
>>>
> 
>