Re: [PATCH 06/13] dt-bindings: rng: add bindings for microchip mpfs rng

From: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
To: Conor.Dooley@microchip.com
Cc: broonie@kernel.org, aou@eecs.berkeley.edu, robh+dt@kernel.org,
	linus.walleij@linaro.org, bgolaszewski@baylibre.com,
	palmer@dabbelt.com, paul.walmsley@sifive.com,
	jassisinghbrar@gmail.com, atish.patra@wdc.com,
	Daire.McNamara@microchip.com, Lewis.Hanly@microchip.com,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
	geert@linux-m68k.org, linux-gpio@vger.kernel.org,
	linux-riscv@lists.infradead.org, linux-crypto@vger.kernel.org,
	linux-usb@vger.kernel.org, bin.meng@windriver.com,
	linux-i2c@vger.kernel.org, alexandre.belloni@bootlin.com,
	Ivan.Griffin@microchip.com, linux-rtc@vger.kernel.org,
	linux-spi@vger.kernel.org, a.zummo@towertech.it,
	gregkh@linuxfoundation.org
Subject: Re: [PATCH 06/13] dt-bindings: rng: add bindings for microchip mpfs rng
Date: Tue, 9 Nov 2021 13:56:51 +0100	[thread overview]
Message-ID: <ca17d6ac-ef8e-b01c-3278-7cbb0d5745e3@canonical.com> (raw)
In-Reply-To: <71c6917e-1463-c708-550a-726e5fe1566d@microchip.com>

On 09/11/2021 13:54, Conor.Dooley@microchip.com wrote:
> On 08/11/2021 21:16, Krzysztof Kozlowski wrote:
>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>
>> On 08/11/2021 16:05, conor.dooley@microchip.com wrote:
>>> From: Conor Dooley <conor.dooley@microchip.com>
>>>
>>> Add device tree bindings for the hardware rng device accessed via
>>> the system services on the Microchip PolarFire SoC.
>>>
>>> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
>>> ---
>>>   .../bindings/rng/microchip,mpfs-rng.yaml      | 31 +++++++++++++++++++
>>>   1 file changed, 31 insertions(+)
>>>   create mode 100644 Documentation/devicetree/bindings/rng/microchip,mpfs-rng.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/rng/microchip,mpfs-rng.yaml b/Documentation/devicetree/bindings/rng/microchip,mpfs-rng.yaml
>>> new file mode 100644
>>> index 000000000000..e8ecb3538a86
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/rng/microchip,mpfs-rng.yaml
>>> @@ -0,0 +1,31 @@
>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +$id: "http://devicetree.org/schemas/rng/microchip,mpfs-rng.yaml#"
>>> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
>>> +
>>> +title: Microchip MPFS random number generator
>>> +
>>> +maintainers:
>>> +  - Conor Dooley <conor.dooley@microchip.com>
>>> +
>>> +properties:
>>> +  compatible:
>>> +    const: microchip,polarfire-soc-rng
>>> +
>>> +  syscontroller:
>>> +    maxItems: 1
>>> +    description: name of the system controller device node
>>
>> There are several issues with this:
>> 1. You need to describe the type.
>> 2. Description is not helpful (just copying the name of property) and
>> actually misleading because you do not put there the name of device node.
>> 3. What is it? Looks like syscon (or sometimes called sysreg). If yes,
>> please use existing syscon bindings.
> 1 & 2 - Correct, it is bad & I'll write a better description for it.
> 3 - Its a system controller implemented as a mailbox. The syscontroller 
> is the mailbox client, which the rng and generic drivers both use.

I understood that pointed device node is a mailbox, not this node. But
here, what is it here? How do you use it here?

Best regards,
Krzysztof