On Fri, Mar 05, 2021 at 11:46:35AM +0100, Pavel Machek wrote:
> Hi!
> 
> > > > For motorola modem case, we may have a GNSS device on channel 4.
> > > > Let's add that to the binding and example.
> > > > 
> > > > Signed-off-by: Tony Lindgren <tony@atomide.com>
> > > > ---
> > > >  .../devicetree/bindings/serdev/serdev-ngsm.yaml          | 9 +++++++++
> > > >  1 file changed, 9 insertions(+)
> 
> > 
> > And since we're describing a mux, I think you need nodes for the virtual
> > ports rather than a reg property in what should be a serial client. That
> > is something like
> > 
> > 	serial@nnn {
> > 		modem {
> > 			compatible = "etsi,ts27001-mux";
> > 
> > 			serial@4 {
> > 				compatible = "etsi,ts27001-serial";
> > 				reg = <4>;
> > 
> > 				gnss {
> > 					compatible = "motorola,motmdm-gnss";
> > 				};
> > 			};
> > 		};
> > 	};
> > 
> > This way you can actually use serdev for the client drivers (e.g. for
> > gnss), and those drivers also be used for non-muxed ports if needed
> > (e.g. over USB).
> 
> I have done changes you requested, and then hit "serdev is busy
> because it can have at most one child" limit in the code. You have
> pretty clean driver in your inbox, and no reply. No help with serdev
> core limitations, either. Can you start to communicate?

Heh, look at the devicetree example above that I gave you back in March.
It has the virtual serial ports described ("serial@4"), which you were
missing.

Johan