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Date: Thu, 25 Jan 2024 11:22:34 +0200
From: Vladimir Oltean <olteanv@gmail.com>
To: =?utf-8?B?QXLEsW7DpyDDnE5BTA==?= <arinc.unal@arinc9.com>
Cc: Daniel Golle <daniel@makrotopia.org>,
	Landen Chao <Landen.Chao@mediatek.com>,
	DENG Qingfang <dqfext@gmail.com>,
	Sean Wang <sean.wang@mediatek.com>, Andrew Lunn <andrew@lunn.ch>,
	Florian Fainelli <f.fainelli@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>,
	David Bauer <mail@david-bauer.net>, mithat.guner@xeront.com,
	erkin.bozoglu@xeront.com,
	Luiz Angelo Daros de Luca <luizluca@gmail.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org
Subject: Re: [PATCH net-next] net: dsa: mt7530: support OF-based registration
 of switch MDIO bus
Message-ID: <20240125092234.czwjwc3izmsl3ekr@skbuf>
References: <20240122053431.7751-1-arinc.unal@arinc9.com>
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In-Reply-To: <20240122053431.7751-1-arinc.unal@arinc9.com>

On Mon, Jan 22, 2024 at 08:34:31AM +0300, Arınç ÜNAL wrote:
> Currently the MDIO bus of the switches the MT7530 DSA subdriver controls
> can only be registered as non-OF-based. Bring support for registering the
> bus OF-based.
> 
> The subdrivers that control switches [with MDIO bus] probed on OF must
> follow this logic to support all cases properly:
> 
> No switch MDIO bus defined: Populate ds->user_mii_bus, register the MDIO
> bus, set the interrupts for PHYs if "interrupt-controller" is defined at
> the switch node. This case should only be covered for the switches which
> their dt-bindings documentation didn't document the MDIO bus from the
> start. This is to keep supporting the device trees that do not describe the
> MDIO bus on the device tree but the MDIO bus is being used nonetheless.
> 
> Switch MDIO bus defined: Don't populate ds->user_mii_bus, register the MDIO
> bus, set the interrupts for PHYs if ["interrupt-controller" is defined at
> the switch node and "interrupts" is defined at the PHY nodes under the
> switch MDIO bus node].
> 
> Switch MDIO bus defined but explicitly disabled: If the device tree says
> status = "disabled" for the MDIO bus, we shouldn't need an MDIO bus at all.
> Instead, just exit as early as possible and do not call any MDIO API.
> 
> The use of ds->user_mii_bus is inappropriate when the MDIO bus of the
> switch is described on the device tree [1], which is why we don't populate
> ds->user_mii_bus in that case.
> 
> Link: https://lore.kernel.org/netdev/20231213120656.x46fyad6ls7sqyzv@skbuf/ [1]
> Suggested-by: David Bauer <mail@david-bauer.net>
> Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
> ---

Reviewed-by: Vladimir Oltean <olteanv@gmail.com>