Hello Niklas-san,
> From: Niklas Söderlund, Sent: Wednesday, September 4, 2024 2:16 AM
>
> When reading registers from the PHY using the SIOCGMIIREG IOCTL any
> errors returned from either mdiobus_read() or mdiobus_c45_read() are
> ignored, and parts of the returned error is passed as the register value
> back to user-space.
>
> For example, if mdiobus_c45_read() is used with a bus that do not
> implement the read_c45() callback -EOPNOTSUPP is returned. This is
> however directly stored in mii_data->val_out and returned as the
> registers content. As val_out is a u16 the error code is truncated and
> returned as a plausible register value.
>
> Fix this by first checking the return value for errors before returning
> it as the register content.
>
> Before this patch,
>
> # phytool read eth0/0:1/0
> 0xffa1
>
> After this change,
>
> $ phytool read eth0/0:1/0
> error: phy_read (-95)
>
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
Thank you for the patch!
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
And, I tested on my environment (R-Car V4H with RTSN driver), and it works. So,
Tested-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Best regards,
Yoshihiro Shimoda
> ---
> drivers/net/phy/phy.c | 17 +++++++++++------
> 1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> index cba3af926429..4f3e742907cb 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -342,14 +342,19 @@ int phy_mii_ioctl(struct phy_device *phydev, struct ifreq *ifr, int cmd)
> if (mdio_phy_id_is_c45(mii_data->phy_id)) {
> prtad = mdio_phy_id_prtad(mii_data->phy_id);
> devad = mdio_phy_id_devad(mii_data->phy_id);
> - mii_data->val_out = mdiobus_c45_read(
> - phydev->mdio.bus, prtad, devad,
> - mii_data->reg_num);
> + ret = mdiobus_c45_read(phydev->mdio.bus, prtad, devad,
> + mii_data->reg_num);
> +
> } else {
> - mii_data->val_out = mdiobus_read(
> - phydev->mdio.bus, mii_data->phy_id,
> - mii_data->reg_num);
> + ret = mdiobus_read(phydev->mdio.bus, mii_data->phy_id,
> + mii_data->reg_num);
> }
> +
> + if (ret < 0)
> + return ret;
> +
> + mii_data->val_out = ret;
> +
> return 0;
>
> case SIOCSMIIREG:
> --
> 2.46.0
>
