On Fri, Aug 19, 2022 at 2:39 PM Bjorn Andersson <bjorn.andersson@xxxxxxxxxx> wrote: > > On Fri 19 Aug 15:49 CDT 2022, Stephen Boyd wrote: > > > > I like 2 endpoints to represent the usb-c-connector, but that doesn't seem > > > to be compatible (without introducing `data-lanes`, at least) with all > > > the various > > > combinations on the remote side, if that remote side is a DRM bridge with DP > > > output capability (like it6505 or anx7625). > > > That type of DRM bridge supports 1, 2 or 4 lane DP connections. > > > > Why can't the remote side that's a pure DP bridge (it6505) bundle > > however many lanes it wants into one endpoint? If it's a pure DP bridge > > we should design the bridge binding to have up to 4 endpoints, but > > sometimes 2 or 1 and then overlay data-lanes onto that binding so that > > we can tell the driver how to remap the lanes if it can. If the hardware > > can't support remapping lanes then data-lanes shouldn't be in the > > binding. 2 endpoints sounds fine to me. The overloading of the bridge-side endpoint to mean different things depending on what it's connected to seemed odd to me, but if that is acceptable for the bridge binding, then great. > The existing implementation provides the interfaces usb_role_switch, > usb_typec_mux and usb_typec_switch. These works based on the concept > that the USB Type-C controller will request the endpoints connected to > the usb-c-connector about changes such as "switch to host mode", "switch > to 2+2 USB/DP combo" and "switch orientation to reverse". We use this > same operations to inform any endpoint at any port about these events > and they all react accordingly. Right, but that implementation/assumption doesn't work so well when you have 2 Type-C ports which might route to the same bridge (2 lane from each). The other 2 lanes from the other endpoints can go to (say) a USB HUB. > > Perhaps I'm misunderstanding your suggestion, but if you start > representing each individual lane in the SuperSpeed interface I believe > you would have to just abandon this interface and replace it with > something like "give me USB on port@1/endpoint@0 and port@1/endpoint@1 > and give me DP on port@1/endpoint@2 and port@1/endpoint@3". I don't think that is necessary. The switch driver can register the switches ( and it can find out which end-points map to the same usb-c-connector). >From the port driver, the port driver just needs to tell each switch registered for it's port that "I want DP Pin assignment C/ DP Pin assignment D / Plain USB3.x" and the switch driver(s) can figure out what to output on its pins (since the Type-C binding will specify ep0 = A2-A3 (TX1), ep1 = B10-B11 , etc) orientation-switch can tell the switch if the signals need to be swapped around. The above notwithstanding, it sounds like the 2-ep approach has more support than 4 ep-approach, so this specific example is moot.
