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

[Andrew Lunn <andrew@lunn.ch>]

On Thu, Sep 03, 2026 at 06:32:26PM +0530, Parthiban Veerasooran wrote:
> Hi Andrew,
> 
> Thank you for reviewing this patch series.
> 
> On 02/09/26 6:13 am, Andrew Lunn wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> > 
> > On Tue, Sep 01, 2026 at 06:39:47PM +0530, Parthiban Veerasooran wrote:
> > > The integrated PHY has no dedicated interrupt line; its interrupt is
> > > delivered in-band as the PHYINT bit in STATUS0, which raises the MAC-PHY
> > > SPI interrupt via the extended status. phy_mac_interrupt() only triggers
> > > a link-status re-read and cannot make the PHY driver read and acknowledge
> > > its interrupt source registers, so expose the PHY interrupt to phylib as a
> > > nested virtual IRQ instead.
> > > 
> > > Use dummy_irq_chip as the irqchip, map a virtual IRQ and assign it to
> > > phydev->irq before phy_connect_direct() so phylib enters interrupt mode
> > > and uses the PHY driver's config_intr/handle_interrupt. Unmask PHYINT in
> > > INT_MASK0, and when it is seen in the extended status, dispatch
> > > handle_nested_irq() synchronously from the sleepable threaded IRQ. PHYINT
> > > is level triggered, so acking the PHY source there clears it before the
> > > next data chunk, avoiding a storm.
> > 
> > 
> >     9.2.8.7 PHYINT
> > 
> >     Physical Layer Interrupt. When set, this bit indicates a service
> >     request from the underlying physical layer block.  Many physical
> >     layer implementations support an interrupt output for signaling
> >     events to the station controller. This bit is optional and will be
> >     implemented only if the underlying physical layer supports
> >     generating interrupts to a higher level. When implemented, this bit
> >     shall be cleared by acknowledging the underlying physical layer
> >     interrupt source(s). When not implemented, this bit shall be
> >     reserved with a read- only value of zero.
> > 
> > At the moment, phylib is polling the PHY. That is guaranteed to work.
> > 
> > The standard indicates this interrupt is optional. It might not be
> > implemented. phylib assumes that if there is an interrupt, the
> > interrupt works, and it does not poll. So any hardware which does not
> > implement this interrupt is now broken.
> > 
> > Please find a way not to break other devices.
> Thank you for pointing it out. PHYINT is optional per the OA TC6 standard
> (section 9.2.8.7), and unconditionally setting up the virtual IRQ breaks
> devices that do not implement it.
> 
> I checked both the OA TC6 standard (V1.1) and the LAN8650/1 datasheet, and
> there is no capability register bit to detect PHYINT support at runtime.

I also did a quick check of the standard and could not find an
indication if interrupts were support. So a quirks flag does seem to
be the correct solution.

   Andrew