Re: [RFC net-next 0/2] Introduce MDIO probe order C45 over C22

On Tue, Jun 01, 2021 at 03:04:51PM +0200, Andrew Lunn wrote:

quoted

On Tue, Jun 01, 2021 at 06:47:34PM +0800, Wong Vee Khee wrote:

quoted

On Tue, May 25, 2021 at 03:34:34PM +0200, Andrew Lunn wrote:

quoted

On Tue, May 25, 2021 at 01:58:03PM +0800, Wong Vee Khee wrote:

quoted

Synopsys MAC controller is capable of pairing with external PHY devices
that accessible via Clause-22 and Clause-45.

There is a problem when it is paired with Marvell 88E2110 which returns
PHY ID of 0 using get_phy_c22_id(). We can add this check in that
function, but this will break swphy, as swphy_reg_reg() return 0. [1]

Is it possible to identify it is a Marvell PHY? Do any of the other
C22 registers return anything unique? I'm wondering if adding
.match_phy_device to genphy would work to identify it is a Marvell PHY
and not bind to it. Or we can turn it around, make the
.match_phy_device specifically look for the fixed-link device by
putting a magic number in one of the vendor registers.

I checked the Marvell and did not see any unique register values.
Also, since get_phy_c22_id() returns a *phy_id== 0, it is not bind to
any PHY driver, so I don't think adding the match_phy_device check in
getphy would help.

It has a Marvell ID in C45 space. So maybe we need to special case for
ID 0. If we get that, go look in C45 space. If we find a valid ID, use
it. If we get EOPNOTSUP because the MDIO bus is not C45 capable, or we
don't find a vendor ID in C45 space, keep with id == 0 and load
genphy?

Make sense for me.
Let me what you think of adding the checks in *get_phy_device():

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 1539ea021ac0..ad9a87fadea1 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c

@@ -862,11 +862,21 @@ struct phy_device *get_phy_device(struct mii_bus *bus, int addr, bool is_c45)
        c45_ids.mmds_present = 0;
        memset(c45_ids.device_ids, 0xff, sizeof(c45_ids.device_ids));

-       if (is_c45)
+       if (is_c45) {
                r = get_phy_c45_ids(bus, addr, &c45_ids);
-       else
+       } else {
                r = get_phy_c22_id(bus, addr, &phy_id);

+               if (phy_id == 0) {
+                       r = get_phy_c45_ids(bus, addr, &c45_ids);
+                       if (r == -ENOTSUPP || r == -ENODEV)
+                               return 0;