Re: [PATCH v3] net: phy: air_en8811h: add AN8811HB MCU assert/deassert support

[Paolo Abeni <pabeni@redhat.com>]

On 4/20/26 3:45 PM, Lucien.Jheng wrote:
> AN8811HB needs a MCU soft-reset cycle before firmware loading begins.
> Assert the MCU (hold it in reset) and immediately deassert (release)
> via a dedicated PBUS register pair (0x5cf9f8 / 0x5cf9fc), accessed
> through a registered mdio_device at PHY-addr+8.
> 
> Add __air_pbus_reg_write() as a low-level helper taking a struct
> mdio_device *, create and register the PBUS mdio_device in
> an8811hb_probe() and store it in priv->pbusdev, then implement
> an8811hb_mcu_assert() / _deassert() on top of it. Add
> an8811hb_remove() to unregister the PBUS device on teardown. Wire
> both calls into an8811hb_load_firmware() and en8811h_restart_mcu()
> so every firmware load or MCU restart on AN8811HB correctly sequences
> the reset control registers.
> 
> Fixes: 0a55766b7711 ("net: phy: air_en8811h: add Airoha AN8811HB support")

The hash is incorrect, should be 5afda1d734ed

[...]
> @@ -254,6 +267,31 @@ static int air_phy_write_page(struct phy_device *phydev, int page)
>  	return __phy_write(phydev, AIR_EXT_PAGE_ACCESS, page);
>  }
>  
> +static int __air_pbus_reg_write(struct mdio_device *mdiodev,
> +				u32 pbus_reg, u32 pbus_data)
> +{
> +	int ret;
> +
> +	ret = __mdiobus_write(mdiodev->bus, mdiodev->addr, AIR_EXT_PAGE_ACCESS,
> +			      upper_16_bits(pbus_reg));
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = __mdiobus_write(mdiodev->bus, mdiodev->addr, AIR_PBUS_ADDR_HIGH,
> +			      (pbus_reg & GENMASK(15, 6)) >> 6);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = __mdiobus_write(mdiodev->bus, mdiodev->addr,
> +			      (pbus_reg & GENMASK(5, 2)) >> 2,
> +			      lower_16_bits(pbus_data));
> +	if (ret < 0)
> +		return ret;
> +
> +	return __mdiobus_write(mdiodev->bus, mdiodev->addr, AIR_PBUS_DATA_HIGH,
> +			       upper_16_bits(pbus_data));

Sashiko says:

Will writing the lower 16 bits before the upper 16 bits cause the
hardware transaction to fire with stale upper data?
The __air_buckpbus_reg_write() helper triggers the 32-bit transaction
using the lower 16 bits as the execution trigger. If this hardware
behaves similarly, should AIR_PBUS_DATA_HIGH be populated before writing
the lower 16 bits?

[...]
> @@ -1175,10 +1281,22 @@ static int an8811hb_probe(struct phy_device *phydev)
>  		return -ENOMEM;
>  	phydev->priv = priv;
>  
> +	mdiodev = mdio_device_create(phydev->mdio.bus,
> +				     phydev->mdio.addr + EN8811H_PBUS_ADDR_OFFS);

Sashiko says:

Can this create an out-of-bounds array access if the base PHY address is
high?
The mdio_map array in struct mii_bus has a fixed size of PHY_MAX_ADDR (32).
If phydev->mdio.addr is 24 or higher, adding EN8811H_PBUS_ADDR_OFFS (8)
will result in an address of 32 or more.
Neither mdio_device_create() nor mdio_device_register() validate that
the address is within PHY_MAX_ADDR. When mdiobus_register_device()
executes mdiodev->bus->mdio_map[mdiodev->addr] = mdiodev, could this
write past the end of the array and corrupt adjacent memory?

/P