[PATCH v2] net: usb: asix_devices: add phy_mask for ax88772 mdio bus

[PATCH v2] net: usb: asix_devices: add phy_mask for ax88772 mdio bus

[Xu Yang]

Without setting phy_mask for ax88772 mdio bus, current driver may create
at most 32 mdio phy devices with phy address range from 0x00 ~ 0x1f.
DLink DUB-E100 H/W Ver B1 is such a device. However, only one main phy
device will bind to net phy driver. This is creating issue during system
suspend/resume since phy_polling_mode() in phy_state_machine() will
directly deference member of phydev->drv for non-main phy devices. Then
NULL pointer dereference issue will occur. Due to only external phy or
internal phy is necessary, add phy_mask for ax88772 mdio bus to workarnoud
the issue.

Closes: https://lore.kernel.org/netdev/20250806082931.3289134-1-xu.yang_2@nxp.com
Fixes: e532a096be0e ("net: usb: asix: ax88772: add phylib support")
Cc: stable@vger.kernel.org
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>

---
Changes in v2:
 - fix the issue in asix_devices driver
---
 drivers/net/usb/asix_devices.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/usb/asix_devices.c b/drivers/net/usb/asix_devices.c
index ac28f5fe7ac2..8d50b2c7e1be 100644
--- a/drivers/net/usb/asix_devices.c
+++ b/drivers/net/usb/asix_devices.c
@@ -676,6 +676,7 @@ static int ax88772_init_mdio(struct usbnet *dev)
 	priv->mdio->read = &asix_mdio_bus_read;
 	priv->mdio->write = &asix_mdio_bus_write;
 	priv->mdio->name = "Asix MDIO Bus";
+	priv->mdio->phy_mask = ~(BIT(priv->phy_addr) | BIT(AX_EMBD_PHY_ADDR));
 	/* mii bus name is usb-<usb bus number>-<usb device number> */
 	snprintf(priv->mdio->id, MII_BUS_ID_SIZE, "usb-%03d:%03d",
 		 dev->udev->bus->busnum, dev->udev->devnum);
-- 
2.34.1

Re: [PATCH v2] net: usb: asix_devices: add phy_mask for ax88772 mdio bus

[Jakub Kicinski]

On Mon, 11 Aug 2025 17:29:31 +0800 Xu Yang wrote:
> Without setting phy_mask for ax88772 mdio bus, current driver may create
> at most 32 mdio phy devices with phy address range from 0x00 ~ 0x1f.
> DLink DUB-E100 H/W Ver B1 is such a device. However, only one main phy
> device will bind to net phy driver. This is creating issue during system
> suspend/resume since phy_polling_mode() in phy_state_machine() will
> directly deference member of phydev->drv for non-main phy devices. Then
> NULL pointer dereference issue will occur. Due to only external phy or
> internal phy is necessary, add phy_mask for ax88772 mdio bus to workarnoud
> the issue.

Andrew, Oleksij, this looks like v2 of
https://lore.kernel.org/all/20250806082931.3289134-1-xu.yang_2@nxp.com/
are you willing to venture a Review tag here ? :)

Re: [PATCH v2] net: usb: asix_devices: add phy_mask for ax88772 mdio bus

[Oleksij Rempel]

On Mon, Aug 11, 2025 at 05:29:31PM +0800, Xu Yang wrote:
> Without setting phy_mask for ax88772 mdio bus, current driver may create
> at most 32 mdio phy devices with phy address range from 0x00 ~ 0x1f.
> DLink DUB-E100 H/W Ver B1 is such a device. However, only one main phy
> device will bind to net phy driver. This is creating issue during system
> suspend/resume since phy_polling_mode() in phy_state_machine() will
> directly deference member of phydev->drv for non-main phy devices. Then
> NULL pointer dereference issue will occur. Due to only external phy or
> internal phy is necessary, add phy_mask for ax88772 mdio bus to workarnoud
> the issue.
> 
> Closes: https://lore.kernel.org/netdev/20250806082931.3289134-1-xu.yang_2@nxp.com
> Fixes: e532a096be0e ("net: usb: asix: ax88772: add phylib support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Xu Yang <xu.yang_2@nxp.com>

Tested-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>

Thank you! 
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Re: [PATCH v2] net: usb: asix_devices: add phy_mask for ax88772 mdio bus

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Paolo Abeni <pabeni@redhat.com>:

On Mon, 11 Aug 2025 17:29:31 +0800 you wrote:
> Without setting phy_mask for ax88772 mdio bus, current driver may create
> at most 32 mdio phy devices with phy address range from 0x00 ~ 0x1f.
> DLink DUB-E100 H/W Ver B1 is such a device. However, only one main phy
> device will bind to net phy driver. This is creating issue during system
> suspend/resume since phy_polling_mode() in phy_state_machine() will
> directly deference member of phydev->drv for non-main phy devices. Then
> NULL pointer dereference issue will occur. Due to only external phy or
> internal phy is necessary, add phy_mask for ax88772 mdio bus to workarnoud
> the issue.
> 
> [...]

Here is the summary with links:
  - [v2] net: usb: asix_devices: add phy_mask for ax88772 mdio bus
    https://git.kernel.org/netdev/net/c/4faff70959d5

You are awesome, thank you!
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