[PATCH v2] PCI: dwc: Make Link Up IRQ logic handle already powered on PCIe switches

[Manivannan Sadhasivam]

On Fri, Dec 12, 2025 at 03:37:26PM +0900, Niklas Cassel wrote:
> Hello Mani,
> 
> On Fri, Dec 12, 2025 at 12:52:35PM +0900, Manivannan Sadhasivam wrote:
> > > This patch missed the v6.19 merge window (and so did the pwrctrl rework
> > > series), so as long as Mani queues up both for v6.20 (with the pwrctrl
> > > rework series getting applied first), I think we are good.
> > > 
> > 
> > The plan is to merge pwrctrl series to v6.20 (unless we get strong objections),
> > but once that happens, Qcom doesn't need this patch.
> > 
> > So it'd be good if you can just limit this patch to just Rockchip. Then once the
> > Rockchip also moves to pwrctrl, we can revert this patch (also the whole IRQ
> > based link up since the Root Port is not hotplug capable).
> 
> The main reason why I did not like a revert, was because it would remove
> the nice feature where the bus is enumerated automatically on link up.
> 
> I assumed that the plan was to add Link Up IRQ support in pwrctrl in the
> future.
> 

As I dig more and more into pwrctrl, it becomes clear to me that emulating
hotplug on non-hotplug capable hw is a bad idea. Though it gives a nice user
experience in majority of the cases, it also gives issue in some cases like
switch. So pwrctrl will just power on all devices/slots before initial bus scan
and will not do any link up based enumeration later. And neither the controller
driver.

> If that is not the case, and the plan is instead to eventually remove the
> existing Link Up IRQ support, then perhaps you could simply apply patches
> from:
> https://lore.kernel.org/linux-pci/20251111105100.869997-8-cassel@kernel.org/
> 
> Either the whole series or just patch 1 and 2, maintainer's choice :)
> 

I tried applying the whole series, but it fails at patch 2. Could you please
rebase against, pci/controller/dwc and repost?

- Mani

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