Re: [RFC PATCH] net: phy/mdio: enable mmd indirect access through phy_mii_ioctl()

[Grygorii Strashko]

On 02/11/2021 20:37, Grygorii Strashko wrote:
> Hi Russell, Andrew,
>
> Thanks a lot for you comments.
>
> On 02/11/2021 19:41, Russell King (Oracle) wrote:
> > On Tue, Nov 02, 2021 at 07:19:46PM +0200, Grygorii Strashko wrote:
> > > It would require MDIO bus lock, which is not a solution,
> > > or some sort of batch processing, like for mmd:
> > >   w reg1 val1
> > >   w reg2 val2
> > >   w reg1 val3
> > >   r reg2
> > >
> > > What Kernel interface do you have in mind?
> >
> > That is roughly what I was thinking, but Andrew has basically said no
> > to it.
> >
> > > Sry, but I have to note that demand for this become terribly high, min two pings in months
> >
> > Feel free to continue demanding it, but it seems that at least two of
> > the phylib maintainers are in agreement that providing generic
> > emulation of C45 accesses in kernel space is just not going to happen.
>
> not ready to give up.
>
> One more idea how about mdiobus_get_phy(), so we can search for PHY and
> if present try to use proper API phy_read/phy_write_mmd?

smth like below
diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index a3bfb156c83d..8ebe59b5647d 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -285,6 +285,7 @@ int phy_mii_ioctl(struct phy_device *phydev, struct ifreq *ifr, int cmd)
        u16 val = mii_data->val_in;
        bool change_autoneg = false;
        int prtad, devad;
+       struct phy_device *phydev_rq = phydev;
 
        switch (cmd) {
        case SIOCGMIIPHY:
@@ -300,8 +301,18 @@ int phy_mii_ioctl(struct phy_device *phydev, struct ifreq *ifr, int cmd)
                        prtad = mii_data->phy_id;
                        devad = mii_data->reg_num;
                }
-               mii_data->val_out = mdiobus_read(phydev->mdio.bus, prtad,
-                                                devad);
+
+               if (prtad != phydev->mdio.addr)
+                       phydev_rq = mdiobus_get_phy(phydev->mdio.bus, prtad);
+
+               if (!phydev_rq) {
+                       mii_data->val_out = mdiobus_read(phydev->mdio.bus, prtad, devad);
+               } else if (mdio_phy_id_is_c45(mii_data->phy_id) && !phydev->is_c45) {
+                       mii_data->val_out = phy_read_mmd(phydev_rq, mdio_phy_id_devad(mii_data->phy_id), mii_data->reg_num);
+               } else {
+                       mii_data->val_out = phy_read(phydev_rq, mii_data->reg_num);
+               }
+
                return 0;
 
        case SIOCSMIIREG:

--
Best regards,
grygorii