On 05.01.2019 14:21, Heiner Kallweit wrote:
> During a bug analysis we came across the fact that there's no guarantee
> that reading from the ID registers returns a valid value if PHY is
> powered down. When reading invalid values we may load no or the wrong
> PHY driver. Therefore let's play safe and power up the PHY before
> reading the ID registers in case PHY is powered down.
>
Fixes: 02a6efcab675 ("net: phy: allow scanning busses with missing phys")
> Suggested-by: Florian Fainelli <f.faine...@gmail.com>
> Signed-off-by: Heiner Kallweit <hkallwe...@gmail.com>
> ---
> drivers/net/phy/phy_device.c | 23 +++++++++++++----------
> 1 file changed, 13 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 9560a2b84..d4702313d 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -754,19 +754,22 @@ static int get_phy_id(struct mii_bus *bus, int addr,
> u32 *phy_id,
> if (is_c45)
> return get_phy_c45_ids(bus, addr, phy_id, c45_ids);
>
> + phy_reg = mdiobus_read(bus, addr, MII_BMCR);
> + if (phy_reg < 0)
> + /* returning -ENODEV allows to continue bus-scanning */
> + return (phy_reg == -EIO || phy_reg == -ENODEV) ? -ENODEV : -EIO;
> +
> + /* PHY may be powered down and ID registers invalid */
> + if (phy_reg & BMCR_PDOWN) {
> + mdiobus_write(bus, addr, MII_BMCR, phy_reg & ~BMCR_PDOWN);
> + /* give the PHY some time to resume */
> + msleep(100);
> + }
> +
> /* Grab the bits from PHYIR1, and put them in the upper half */
> phy_reg = mdiobus_read(bus, addr, MII_PHYSID1);
> - if (phy_reg < 0) {
> - /* if there is no device, return without an error so scanning
> - * the bus works properly
> - */
> - if (phy_reg == -EIO || phy_reg == -ENODEV) {
> - *phy_id = 0xffffffff;
> - return 0;
> - }
> -
> + if (phy_reg < 0)
> return -EIO;
> - }
>
> *phy_id = (phy_reg & 0xffff) << 16;
>
>
