Message-ID: <514ec4b8-ef78-35c1-2215-22884fca87d4@kernel.org>
Date:   Wed, 8 Feb 2023 21:08:40 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.7.1
Subject: Re: [PATCH v2 03/11] dt-bindings: arm: mediatek: add
 'mediatek,pn_swap' property
Content-Language: en-US
To:     Daniel Golle <daniel@makrotopia.org>
Cc:     netdev@vger.kernel.org, linux-mediatek@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Russell King <linux@armlinux.org.uk>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Lorenzo Bianconi <lorenzo@kernel.org>,
        Mark Lee <Mark-MC.Lee@mediatek.com>,
        John Crispin <john@phrozen.org>, Felix Fietkau <nbd@nbd.name>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        DENG Qingfang <dqfext@gmail.com>,
        Landen Chao <Landen.Chao@mediatek.com>,
        Sean Wang <sean.wang@mediatek.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Eric Dumazet <edumazet@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        Vladimir Oltean <olteanv@gmail.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Jianhui Zhao <zhaojh329@gmail.com>,
        =?UTF-8?Q?Bj=c3=b8rn_Mork?= <bjorn@mork.no>
References: <cover.1675779094.git.daniel@makrotopia.org>
 <a8c567cf8c3ec6fef426b64fb1ab7f6e63a0cc07.1675779094.git.daniel@makrotopia.org>
 <ad09a065-c10d-3061-adbe-c58724cdfde0@kernel.org>
 <Y+KR26aepqlfsjYG@makrotopia.org>
 <b6d782ef-b375-1e73-a384-1ff37c1548a7@kernel.org>
 <Y+Oo9HaqPeNVUANR@makrotopia.org>
From:   Krzysztof Kozlowski <krzk@kernel.org>
In-Reply-To: <Y+Oo9HaqPeNVUANR@makrotopia.org>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 08/02/2023 14:51, Daniel Golle wrote:
> On Wed, Feb 08, 2023 at 10:32:53AM +0100, Krzysztof Kozlowski wrote:
>> On 07/02/2023 19:00, Daniel Golle wrote:
>>> ...
>>>> 3. Does not look like property of this node. This is a clock controller
>>>> or system controller, not SGMII/phy etc.
>>>
>>> The register range referred to by this node *does* represent also an
>>> SGMII phy. These sgmiisys nodes also carry the 'syscon' compatible, and
>>> are referenced in the node of the Ethernet core, and then used by
>>> drivers/net/ethernet/mediatek/mtk_sgmii.c using syscon_node_to_regmap.
>>> (This is the current situation already, and not related to the patchset
>>> now adding only a new property to support hardware which needs that)
>>
>> Just because a register is located in syscon block, does not mean that
>> SGMII configuration is a property of this device.
> 
> It's not just one register, the whole SGMII PCS is located in those
> mediatek,sgmiisys syscon nodes.

Then maybe this should be a PCS PHY device instead of adding properties
unrelated to clock/system controller? I don't know, currently this
binding says it is a provider of clocks...

> 
>>
>>>
>>> So: Should I introduce a new binding for the same compatible strings
>>> related to the SGMII PHY features? Or is it fine in this case to add
>>> this property to the existing binding?
>>
>> The user of syscon should configure it. I don't think you need new
>> binding. You just have to update the user of this syscon.
> 
> Excuse my confusion, but it's still not entirely clear to me.
> So in this case I should add the description of the added propterty of
> the individual SGMII units (there can be more than one) to
> Documentation/devicetree/bindings/net/mediatek,net.yaml
> eventhough the properties are in the sgmiisys syscon nodes?

I guess the property should be in the node representing the SGMII. You
add it now to the clock (or system) controller, so it does not look
right. It's not a property of a clock controller.

Now which node should have this property depends on your devices - which
I have no clue about, I read what is in the bindings.

> 
> If so I will have to figure out how to describe properties of other
> nodes in the binding of the node referencing them. Are there any
> good examples for that?

phys and pcs'es?

> 
> Or should the property itself be moved into yet another array of
> booleans which should be added in the node describing the ethernet
> controller and referencing these sgmiisys syscons using phandles?

Best regards,
Krzysztof