Re: [PATCH v3 4/9] pci: pwrctrl: generic: support for the UPD720201/UPD720202 USB 3.0 xHCI Host Controller

[Manivannan Sadhasivam]

On Mon, Feb 09, 2026 at 03:59:20PM +0100, Neil Armstrong wrote:
> On 2/9/26 15:49, Manivannan Sadhasivam wrote:
> > On Mon, Feb 09, 2026 at 03:00:02PM +0100, Neil Armstrong wrote:
> > > On 2/9/26 12:30, Manivannan Sadhasivam wrote:
> > > > On Fri, Feb 06, 2026 at 03:50:32PM +0100, Neil Armstrong wrote:
> > > > > Enable the generic pwrctrl driver to control the power of the
> > > > > PCIe UPD720201/UPD720202 USB 3.0 xHCI Host Controller.
> > > > > 
> > > > > Signed-off-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
> > > > > ---
> > > > >    drivers/pci/pwrctrl/generic.c | 4 ++++
> > > > >    1 file changed, 4 insertions(+)
> > > > > 
> > > > > diff --git a/drivers/pci/pwrctrl/generic.c b/drivers/pci/pwrctrl/generic.c
> > > > > index 08e53243cdbd..4a57a631362f 100644
> > > > > --- a/drivers/pci/pwrctrl/generic.c
> > > > > +++ b/drivers/pci/pwrctrl/generic.c
> > > > > @@ -73,6 +73,10 @@ static const struct of_device_id pci_pwrctrl_slot_of_match[] = {
> > > > >    	{
> > > > >    		.compatible = "pciclass,0604",
> > > > >    	},
> > > > > +	/* Renesas UPD720201/UPD720202 USB 3.0 xHCI Host Controller */
> > > > > +	{
> > > > > +		.compatible = "pci1912,0014",
> > > > 
> > > > No need to add the compatible to the driver. Just use the existing compatible as
> > > > fallback in the binding/dts.
> > > 
> > > ???
> > > 
> > > Sorry but this is insane, in no world a standalone PCIe USB controller could be qualified as
> > > compatible as a pciclass,0604 slot.
> > > 
> > 
> > AFAIU, 'compatibility' implies that the driver can safely fallback and would
> > still work. If we add dedicated compatibles for each endpoint devices, then we
> > will just keep adding forever. Powering up a PCIe slot and an endpoint device
> > are conceptually same.
> 
> We're not speaking about driver here, but about compatible string which describes
> a device, a PCI endpoint and a PCIe slot are 2 very different devices that are
> nowhere compatible.
> 
> > 
> > > Technically it would work just fine, but "compatibility" has a meaning....
> > > 
> > 
> > I view compatibility interms of device operation, not device as a whole. But
> > sure, I could be wrong. If the DT maintainers say so, I won't insist.
> 
> In the actual way it's defined _today_, the "slot" and "endpoint" power up schemes are
> compatible, but I hope the slot bindings will get much more features to describe the
> real world slots power properties. And no, endpoints will definitely not have the same
> features as slots, using it as a fallback today is an error.
> 
> On the other side, adding a "simple-pci-endpoint" compatible that enables any supply
> and clock would be a good solution, if the DT maintainers agrees of course.
> 

We do have a 'pci-host-cam-generic' compatible. So we can also have something
like 'pci-pwrctrl-generic' IMO.

- Mani

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