Received-SPF: pass (google.com: domain of linux-kernel+bounces-90939-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Message-ID: <70a00ad4-ee8e-4325-af09-b013247a003a@bootlin.com>
Date: Mon, 4 Mar 2024 17:31:59 +0100
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH net-next 1/3] dt-bindings: net: dp83822: support
 configuring RMII master/slave mode
Content-Language: en-US
To: Andrew Lunn <andrew@lunn.ch>
Cc: "David S. Miller" <davem@davemloft.net>,
 Eric Dumazet <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>,
 Paolo Abeni <pabeni@redhat.com>, Rob Herring <robh+dt@kernel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
 Conor Dooley <conor+dt@kernel.org>, Heiner Kallweit <hkallweit1@gmail.com>,
 Russell King <linux@armlinux.org.uk>, Andrew Davis <afd@ti.com>,
 netdev@vger.kernel.org, devicetree@vger.kernel.org,
 linux-kernel@vger.kernel.org, Thomas Petazzoni
 <thomas.petazzoni@bootlin.com>, =?UTF-8?Q?Miqu=C3=A8l_Raynal?=
 <miquel.raynal@bootlin.com>, Yen-Mei Goh <yen-mei.goh@keysight.com>,
 Maxime Chevallier <maxime.chevallier@bootlin.com>
References: <20240222103117.526955-1-jeremie.dautheribes@bootlin.com>
 <20240222103117.526955-2-jeremie.dautheribes@bootlin.com>
 <d14ba685-dc7e-4f99-a21e-bae9f3e6bc79@lunn.ch>
 <860648fa-11f5-4e0d-ac4e-e81ea111ef31@bootlin.com>
 <68112ecb-532f-4799-912d-16d6ceb9a6f3@lunn.ch>
 <021dbe50-5eb9-4552-b2bb-80d58d3eb076@bootlin.com>
 <d994001c-dff2-402d-bd19-7ddb0c148805@lunn.ch>
From: =?UTF-8?B?SsOpcsOpbWllIERhdXRoZXJpYmVz?=
 <jeremie.dautheribes@bootlin.com>
In-Reply-To: <d994001c-dff2-402d-bd19-7ddb0c148805@lunn.ch>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit

>>> We are normally interested in this 50Mhz reference clock. So i would
>>> drop all references to 25Mhz. It is not relevant to the binding, since
>>> it is nothing to do with connecting the PHY to the MAC, and it has a
>>> fixed value.
>>>
>>> So you can simplify this down to:
>>>
>>> RMII Master: Outputs a 50Mhz Reference clock which can be connected to the MAC.
>>>
>>> RMII Slave: Expects a 50MHz Reference clock input, shared with the
>>> MAC.
>>>
>>>> That said, would you like me to include this description (or some parts) in
>>>> the binding in addition to what I've already written? Or would you prefer me
>>>> to use a more meaningful property name?
>>>
>>> We don't really have any vendor agnostic consistent naming. dp83867
>>> and dp83869 seems to call this ti,clk-output-sel. Since this is
>>> another dp83xxx device, it would be nice if there was consistency
>>> between all these TI devices. So could you check if the concept is the
>>> same, and if so, change dp83826 to follow what other TI devices do.
>>
>>
>> So I had a look at this ti,clk-output-sel property on the TI DP8386x
>> bindings, but unfortunately it does not correspond to our use case. In their
>> case, it is used to select one of the various internal clocks to output on
>> the CLK_OUT pin.
>> In our case, we would prefer to describe the direction of the clock (OUT in
>> master mode, IN in slave mode).
> 
> I would suggest we keep with the current property name, but simplify
> the description. Focus on the reference clock, and ignore the crystal.


Ok noted, thanks for your feedback! I will send a v2 containing a 
simplified description + implement your suggested changes on patch 2.

Jérémie