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Message-ID: <20240107195241.GB132648@kernel.org>
Date: Sun, 7 Jan 2024 19:52:41 +0000
From: Simon Horman <horms@...nel.org>
To: Arınç ÜNAL <arinc.unal@...nc9.com>
Cc: Daniel Golle <daniel@...rotopia.org>,
Landen Chao <Landen.Chao@...iatek.com>,
DENG Qingfang <dqfext@...il.com>,
Sean Wang <sean.wang@...iatek.com>, Andrew Lunn <andrew@...n.ch>,
Florian Fainelli <f.fainelli@...il.com>,
Vladimir Oltean <olteanv@...il.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
Matthias Brugger <matthias.bgg@...il.com>,
AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
David Bauer <mail@...id-bauer.net>, mithat.guner@...ont.com,
erkin.bozoglu@...ont.com,
Luiz Angelo Daros de Luca <luizluca@...il.com>,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH net-next] net: dsa: mt7530: support OF-based registration
of switch MDIO bus
On Sat, Jan 06, 2024 at 03:21:42PM +0300, Arınç ÜNAL wrote:
> From: David Bauer <mail@...id-bauer.net>
>
> 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@...id-bauer.net>
> Signed-off-by: Arınç ÜNAL <arinc.unal@...nc9.com>
> ---
> drivers/net/dsa/mt7530.c | 18 ++++++++++++++----
> 1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> index 391c4dbdff42..39d7e7ad7154 100644
> --- a/drivers/net/dsa/mt7530.c
> +++ b/drivers/net/dsa/mt7530.c
> @@ -2153,17 +2153,25 @@ mt7530_free_irq(struct mt7530_priv *priv)
> static int
> mt7530_setup_mdio(struct mt7530_priv *priv)
> {
> + struct device_node *mnp, *np = priv->dev->of_node;
> struct dsa_switch *ds = priv->ds;
> struct device *dev = priv->dev;
> struct mii_bus *bus;
> static int idx;
> - int ret;
> + int ret = 0;
> +
> + mnp = of_get_child_by_name(np, "mdio");
> +
> + if (mnp && !of_device_is_available(mnp))
> + goto out;
nit: I think it would easier on the eyes to simply
return 0;
>
> bus = devm_mdiobus_alloc(dev);
> if (!bus)
> return -ENOMEM;
>
> - ds->user_mii_bus = bus;
> + if (!mnp)
> + ds->user_mii_bus = bus;
> +
> bus->priv = priv;
> bus->name = KBUILD_MODNAME "-mii";
> snprintf(bus->id, MII_BUS_ID_SIZE, KBUILD_MODNAME "-%d", idx++);
> @@ -2174,16 +2182,18 @@ mt7530_setup_mdio(struct mt7530_priv *priv)
> bus->parent = dev;
> bus->phy_mask = ~ds->phys_mii_mask;
>
> - if (priv->irq)
> + if (priv->irq && !mnp)
> mt7530_setup_mdio_irq(priv);
>
> - ret = devm_mdiobus_register(dev, bus);
> + ret = devm_of_mdiobus_register(dev, bus, mnp);
> + of_node_put(mnp);
> if (ret) {
> dev_err(dev, "failed to register MDIO bus: %d\n", ret);
> if (priv->irq)
> mt7530_free_mdio_irq(priv);
> }
>
> +out:
> return ret;
> }
>
> --
> 2.40.1
>
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