Re: [PATCH net-next 2/3] net: ethernet: oa_tc6: deliver the PHY interrupt to phylib

[Parthiban Veerasooran]

On 03/09/26 7:44 pm, Andrew Lunn wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>
> On Thu, Sep 03, 2026 at 06:53:40PM +0530, Parthiban Veerasooran wrote:
> > Hi Andrew,
> >
> > On 02/09/26 6:00 am, Andrew Lunn wrote:
> > > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> > >
> > > > @@ -600,6 +642,16 @@ static int oa_tc6_phy_init(struct oa_tc6 *tc6)
> > > >                 return -ENODEV;
> > > >         }
> > > >
> > > > +     ret = oa_tc6_phy_irq_setup(tc6);
> > > > +     if (ret) {
> > > > +             oa_tc6_mdiobus_unregister(tc6);
> > > > +             return ret;
> > > > +     }
> > > > +
> > > > +     /* Deliver the PHY interrupt through the nested virtual IRQ. Set before
> > > > +      * phy_connect_direct() so phylib enters interrupt mode.
> > > > +      */
> > > > +     tc6->phydev->irq = tc6->phy_virq;
> > >
> > > I don't know how messy it will be, but it is better to set
> > > mii_bus->irq[] to the interrupt number. phy_device_create() will then
> > > copy it into phydev->irq.
>
> > Thanks for the suggestion. To use mii_bus->irq[] so that phy_device_create()
> > picks it up, we would need to set mii_bus->irq[addr] with created virtual
> > irq number before mdiobus_register(). However, the PHY MDIO address is not
> > known until phy_find_first() returns, so we cannot pre-populate
> > mii_bus->irq[addr] before the bus scan runs.
>
> This is why i made the comment, i did not know how messy it would be.
>
> Where it becomes interesting is the recent patch:
>
> https://patchwork.kernel.org/project/netdevbpf/patch/20260902080511.2211261-3-f@xxxxxx/
>
> It just seems a bit brittle, phydev->irq says one thing, mii_bus->irq[]
> says something else.
>
> Maybe set all member of mii_bus->irq[]?
Thanks for pointing to that patch. Now the concern is clear: 
mdiobus_alloc() initialises all bus->irq[] entries to PHY_POLL, so if 
phydev->irq is set directly without updating mii_bus->irq[], 
phy_restore_genphy_irq() would restore phydev->irq back to PHY_POLL if 
the generic driver ever binds.

So the fix would be to move oa_tc6_phy_irq_setup() before 
mdiobus_register(), populate all mii_bus->irq[] entries with the virtual 
IRQ, and drop the direct phydev->irq assignment. phy_device_create() 
then copies the correct value from bus->irq[addr] during the bus scan, 
keeping both tables consistent.

+     /* Populate all irq[] entries before registration so
+      * phy_device_create() picks up the virtual IRQ regardless of
+      * the PHY's MDIO address.
+      */
+     for (i = 0; i < PHY_MAX_ADDR; i++)
+             tc6->mdiobus->irq[i] = tc6->phy_virq;

      ret = mdiobus_register(tc6->mdiobus);
      if (ret) {
              netdev_err(tc6->netdev, "Could not register MDIO bus\n");
              mdiobus_free(tc6->mdiobus);
              return ret;
      }

Hope this is what expected?

Best regards,
Parthiban V
>        Andrew