[PATCH net-next 1/1] net: phy: fix invalid phy id when probe using C22

When using Clause-22 to probe for PHY devices such as the Marvell
88E2110, PHY ID with value 0 is read from the MII PHYID registers
which caused the PHY framework failed to attach the Marvell PHY
driver.

Fixed this by adding a check of PHY ID equals to all zeroes.

Cc: stable@vger.kernel.org
Reviewed-by: Voon Weifeng <redacted>
Signed-off-by: Wong Vee Khee <redacted>
---
 drivers/net/phy/phy_device.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index a009d1769b08..f1afc00fcba2 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c

@@ -820,8 +820,8 @@ static int get_phy_c22_id(struct mii_bus *bus, int addr, u32 *phy_id)
 
 	*phy_id |= phy_reg;
 
-	/* If the phy_id is mostly Fs, there is no device there */
-	if ((*phy_id & 0x1fffffff) == 0x1fffffff)
+	/* If the phy_id is mostly Fs or all zeroes, there is no device there */
+	if (((*phy_id & 0x1fffffff) == 0x1fffffff) || (*phy_id == 0))
 		return -ENODEV;
 
 	return 0;

-- 
2.25.1

On 16.03.2021 09:57, Wong Vee Khee wrote:

When using Clause-22 to probe for PHY devices such as the Marvell
88E2110, PHY ID with value 0 is read from the MII PHYID registers
which caused the PHY framework failed to attach the Marvell PHY
driver.

The issue occurs with a MAC driver that sets MDIO bus capability
flag MDIOBUS_C22_C45, like stmmac? Or what is the affected MAC
driver?

And if you state it's a fix, a Fixes tag would be needed.

-----Original Message-----
From: Heiner Kallweit <hkallweit1@gmail.com>
Sent: Wednesday, March 17, 2021 4:15 PM
To: Wong, Vee Khee <redacted>; Andrew Lunn
[off-list ref]; Russell King [off-list ref]; David S . Miller
[off-list ref]; Jakub Kicinski [off-list ref]
Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org;
stable@vger.kernel.org; Voon Weifeng [off-list ref]; Ong,
Boon Leong [off-list ref]
Subject: Re: [PATCH net-next 1/1] net: phy: fix invalid phy id when probe
using C22

On 16.03.2021 09:57, Wong Vee Khee wrote:

quoted

When using Clause-22 to probe for PHY devices such as the Marvell
88E2110, PHY ID with value 0 is read from the MII PHYID registers
which caused the PHY framework failed to attach the Marvell PHY
driver.

The issue occurs with a MAC driver that sets MDIO bus capability
flag MDIOBUS_C22_C45, like stmmac? Or what is the affected MAC
driver?

Yes, you are right. This issue is seen when MarvellE2110 is used with
the STMMAC.

And if you state it's a fix, a Fixes tag would be needed.

Noted. Will send a v2 and marked for net.

quoted

Fixed this by adding a check of PHY ID equals to all zeroes.

Cc: stable@vger.kernel.org
Reviewed-by: Voon Weifeng <redacted>
Signed-off-by: Wong Vee Khee <redacted>
---
 drivers/net/phy/phy_device.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index a009d1769b08..f1afc00fcba2 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c

@@ -820,8 +820,8 @@ static int get_phy_c22_id(struct mii_bus *bus, int

addr, u32 *phy_id)

quoted

 	*phy_id |= phy_reg;

-	/* If the phy_id is mostly Fs, there is no device there */
-	if ((*phy_id & 0x1fffffff) == 0x1fffffff)
+	/* If the phy_id is mostly Fs or all zeroes, there is no device there */
+	if (((*phy_id & 0x1fffffff) == 0x1fffffff) || (*phy_id == 0))
 		return -ENODEV;

 	return 0;