[RFC/RFT 4/6] PCI: rockchip-dwc: add pcie bifurcation

[Peter Geis]

On Mon, Apr 18, 2022 at 11:53 AM Bjorn Helgaas <helgaas at kernel.org> wrote:
>
> On Sun, Apr 17, 2022 at 11:08:02AM +0200, Frank Wunderlich wrote:
> > > On Sat, Apr 16, 2022 at 03:54:56PM +0200, Frank Wunderlich wrote:
> > > > From: Frank Wunderlich <frank-w at public-files.de>
> > > >
> > > > PCIe Lanes can be split to 2 slots with bifurcation.
> > > > Add support for this in existing pcie driver.
>
> > > Is the "rockchip,bifurcation" DT property something that should be
> > > generalized so it's not rockchip-specific?  Other controllers are
> > > likely to support similar functionality.
> >
> > I do not know if other controllers support similar functionality,
> > but i ack a property without vendor prefix is better. Should i use
> > "bifurcation" as name or do you think about a different name which
> > is more generic?
>
> Really a question for Rob about what name would be good and where it
> should go.

It might be good to define this as a lane map.
In the Rockchip implementation it's only 2+0 or 1+1, but that isn't
guaranteed if this is made into a standard definition.
So perhaps:
pcie-bifurcation-map = <0>, <1>;
pcie-bifurcation-map = <1>;
pcie-bifurcation-map = <4>, <5>, <6>, <7>;