On 18.03.2021 10:09, 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.
>
> Fixed this by adding a check of PHY ID equals to all zeroes.
>
> Fixes: ee951005e95e ("net: phy: clean up get_phy_c22_id() invalid ID handling")
> Cc: stable@xxxxxxxxxxxxxxx
> Reviewed-by: Voon Weifeng <voon.weifeng@xxxxxxxxx>
> Signed-off-by: Wong Vee Khee <vee.khee.wong@xxxxxxxxx>
> ---
> v2 changelog:
> - added fixes tag
> - marked for net instead of net-next
> ---
> 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 cc38e326405a..c12c30254c11 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -809,8 +809,8 @@ 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;
>
+ the authors of 0cc8fecf041d ("net: phy: Allow mdio buses to auto-probe c45 devices")
In case of MDIOBUS_C22_C45 we probe c22 first, and then c45.
This causes problems with c45 PHY's that have rudimentary c22 support
and return 0 when reading the c22 PHY ID registers.
Is there a specific reason why c22 is probed first? Reversing the order
would solve the issue we speak about here.
c45-probing of c22-only PHY's shouldn't return false positives
(at least at a first glance).
