On Fri, Apr 25, 2025 at 11:20:12AM +0200, Niklas Cassel wrote: > While some boards designs support multiple reference clocking schemes > (e.g. Common Clock and SRNS), and can choose the clocking scheme using > e.g. a DIP switch, most boards designs only support a single clocking > scheme (even if the SoC might support multiple clocking schemes). > > This property is needed such that the PCI controller driver, in endpoint > mode, can set the proper bits, e.g. the Common Clock Configuration bit and > the SRIS Clocking bit, in the PCIe Link Control Register (Offset 10h). > (Sometimes, there are also specific bits that needs to be set in the PHY.) > Thanks for adding the property. I did plan to submit something similar to allow Qcom PCIe EP controllers to run in SRIS mode. > Some device tree bindings have already implemented vendor specific > properties to handle this, e.g. "nvidia,enable-ext-refclk" (Common Clock) > and "nvidia,enable-srns" (SRNS). However, since this property is common > for all PCI controllers running in endpoint mode, this really ought to be > a property in the common pcie-ep.yaml device tree binding. > We should also mark the nvidia specific properties deprecated and use this one. But that's for another follow up series. > Add a new ref-clk-mode property that describes the reference clocking > scheme used by the endpoint. (We do not add a common-clk-ssc option, since > we cannot know/control if the common clock provided by the host uses SSC.) > > Signed-off-by: Niklas Cassel <cassel@xxxxxxxxxx> > --- > Documentation/devicetree/bindings/pci/pci-ep.yaml | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/Documentation/devicetree/bindings/pci/pci-ep.yaml b/Documentation/devicetree/bindings/pci/pci-ep.yaml > index f75000e3093d..206c1dc2ab82 100644 > --- a/Documentation/devicetree/bindings/pci/pci-ep.yaml > +++ b/Documentation/devicetree/bindings/pci/pci-ep.yaml > @@ -42,6 +42,15 @@ properties: > default: 1 > maximum: 16 > > + ref-clk-mode: How about 'refclk-mode' instead of 'ref-clk-mode'? 'refclk' is the most widely used terminology in the bindings. > + description: Reference clocking architechture > + enum: > + - common-clk # Common Reference Clock (provided by RC side) Can we use 'common-clk-host' so that it is explicit that the clock is coming from the host side? - Mani -- மணிவண்ணன் சதாசிவம்
