> Gesendet: Montag, 18. April 2022 um 18:17 Uhr > Von: "Peter Geis" <pgwipeout@xxxxxxxxx> > > 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@xxxxxxxxxxxxxxx> > > > > > > > > > > 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>; how about a lane-map like this (from controllers point of view): rockchip with only 2 lanes (like rk3568): controller 1: lane-map = <1 0>; controller 2: lane-map = <0 1>; here bifurcation is set if a controller does not aquire all lanes.Afaik rk3568 cannot select specific lanes so i end up with bifurcation = true/false (an aggregation-mode on phy) again. but it makes dts-property more usable for other devices/SoC. this contains the maximum of lanes and as mask the lanes to take by the current controller. It is scalable to support more pcie-lanes (x2 x4 x8) example for 2 controllers with PCIe x4 (with 8 lanes available): lane-map=<0 0 0 0 1 1 1 1>; lane-map=<1 1 1 1 0 0 0 0>; of course they can be mixed, if driver supports this. lane-map=<0 1 0 1 0 1 0 1>; lane-map=<1 0 1 0 1 0 1 0>; such lane-map is more flexible regards Frank
