Re: [PATCH v2] PCI: rzg3s-host: Re-enumerate the bus on PCIe link-state changes

[Claudiu Beznea]

Hi, Mani,

On 7/14/26 19:58, Manivannan Sadhasivam wrote:
> On Tue, Jun 30, 2026 at 02:17:20PM +0000, John Madieu wrote:
> > The RZ/G3E PCIe controller does not expose the standard PCIe Slot
> > Capability registers, so the generic pciehp driver cannot be used. The
> > only link-state signal the hardware provides is the DL_UpDown bit in the
> > PEIS0 event status register, which is raised on every Data Link layer
> > up/down transition.
> >
> > Enable DL_UpDown in PEIE0 and hook up an interrupt handler so the driver
> > can react to link-state changes: a device that trains after boot gets
> > enumerated, and a device that disappears on link loss is removed. This
> > provides hotplug-like behaviour without the PCI hotplug core, which is
> > unavailable for the reason above.
> >
> > On a DL_UpDown event the handler acks the W1C status bit and schedules a
> > worker that inspects PCSTAT1.DL_DOWN_STS:
> >
> >    - link up: re-run max link speed negotiation, wait for the link to
> >      settle and pci_rescan_bus() the root bus;
> >    - link down: walk the bus in reverse and
> >      pci_stop_and_remove_bus_device() each child.
> >
> > Both paths take pci_lock_rescan_remove() to serialise against the PCI
> > core.
> >
> > Link events are only acted upon once the controller is fully
> > initialised. A DL_UpDown latched while the registers are not configured,
> > for example when the event IRQ is used as a system wakeup source during
> > resume, is acknowledged but does not schedule a rescan.
> This is not correct. I don't see the patch configuring 'event IRQ' as a wakeup
> source.
>
> Rest of the patch LGTM. If you confirm above, I can reword while applying.

John is not with Renesas anymore so I confirm on his behalf it is OK for you to 
amend it while applying.

However, I checked if this patch applies on top of next-20260715 or v7.2-rc1 and 
it doesn't on neither of these two HEADs.

I can re-base and re-send. Please let me know otherwise.

Thank you,
Claudiu