On 10.10.2019 21:12, Marek Vasut wrote:
> The KSZ8051 PHY and the KSZ8794/KSZ8795/KSZ8765 switch share exactly the
> same PHY ID. Since KSZ8051 is higher in the ksphy_driver[] list of PHYs
> in the micrel PHY driver, it is used even with the KSZ87xx switch. This
> is wrong, since the KSZ8051 configures registers of the PHY which are
> not present on the simplified KSZ87xx switch PHYs and misconfigures
> other registers of the KSZ87xx switch PHYs.
>
> Fortunatelly, it is possible to tell apart the KSZ8051 PHY from the
> KSZ87xx switch by checking the Basic Status register Bit 0, which is
> read-only and indicates presence of the Extended Capability Registers.
> The KSZ8051 PHY has those registers while the KSZ87xx switch does not.
>
> This patch implements simple check for the presence of this bit for
> both the KSZ8051 PHY and KSZ87xx switch, to let both use the correct
> PHY driver instance.
>
> Signed-off-by: Marek Vasut <ma...@denx.de>
> Cc: Andrew Lunn <and...@lunn.ch>
> Cc: David S. Miller <da...@davemloft.net>
> Cc: Florian Fainelli <f.faine...@gmail.com>
> Cc: George McCollister <george.mccollis...@gmail.com>
> Cc: Heiner Kallweit <hkallwe...@gmail.com>
> Cc: Tristram Ha <tristram...@microchip.com>
> Cc: Woojung Huh <woojung....@microchip.com>
> ---
> NOTE: It was also suggested to populate phydev->dev_flags to discern
> the PHY from the switch, this does not work for setups where
> the switch is used as a PHY without a DSA driver. Checking the
> BMSR Bit 0 for Extended Capability Register works for both DSA
> and non-DSA usecase.
> ---
> drivers/net/phy/micrel.c | 30 ++++++++++++++++++++++++++++++
> 1 file changed, 30 insertions(+)
>
> diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
> index 2fea5541c35a..54d483de024f 100644
> --- a/drivers/net/phy/micrel.c
> +++ b/drivers/net/phy/micrel.c
> @@ -341,6 +341,22 @@ static int ksz8041_config_aneg(struct phy_device *phydev)
> return genphy_config_aneg(phydev);
> }
>
> +static int ksz8051_match_phy_device(struct phy_device *phydev)
> +{
> + int ret;
> +
> + ret = phy_read(phydev, MII_BMSR);
> + if (ret < 0)
> + return ret;
> +
> + /* KSZ8051 PHY and KSZ8794/KSZ8795/KSZ8765 switch share the same
> + * exact PHY ID. However, they can be told apart by the extended
> + * capability registers presence. The KSZ8051 PHY has them while
> + * the switch does not.
> + */
> + return ret & BMSR_ERCAP;
Idea and approach are right, but as-is could result in this driver
matching any (even non-Micrel) PHY devices with this bit set. You have
to check the PHY ID too. See Realtek PHY driver for an example.
> +}
> +
> static int ksz8081_config_init(struct phy_device *phydev)
> {
> /* KSZPHY_OMSO_FACTORY_TEST is set at de-assertion of the reset line
> @@ -364,6 +380,18 @@ static int ksz8061_config_init(struct phy_device *phydev)
> return kszphy_config_init(phydev);
> }
>
> +static int ksz8795_match_phy_device(struct phy_device *phydev)
> +{
> + int ret;
> +
> + ret = phy_read(phydev, MII_BMSR);
> + if (ret < 0)
> + return ret;
> +
> + /* See comment in ksz8051_match_phy_device() for details. */
> + return !(ret & BMSR_ERCAP);
> +}
> +
> static int ksz9021_load_values_from_of(struct phy_device *phydev,
> const struct device_node *of_node,
> u16 reg,
> @@ -1029,6 +1057,7 @@ static struct phy_driver ksphy_driver[] = {
> .get_sset_count = kszphy_get_sset_count,
> .get_strings = kszphy_get_strings,
> .get_stats = kszphy_get_stats,
> + .match_phy_device = ksz8051_match_phy_device,
If callback match_phy_device is implemented, then you can remove
phy_id and phy_id_mask. Check phy_bus_match().
> .suspend = genphy_suspend,
> .resume = genphy_resume,
> }, {
> @@ -1148,6 +1177,7 @@ static struct phy_driver ksphy_driver[] = {
> .config_init = kszphy_config_init,
> .config_aneg = ksz8873mll_config_aneg,
> .read_status = ksz8873mll_read_status,
> + .match_phy_device = ksz8795_match_phy_device,
> .suspend = genphy_suspend,
> .resume = genphy_resume,
> }, {
>
