On Thu, Mar 27, 2014 at 10:18 AM, Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> wrote: > On Thu, Mar 27, 2014 at 08:54:09AM -0500, Rob Herring wrote: >> >> >> >> > This however comes back to the more general issue of serial port device >> >> > naming: Linux traditionally uses separate names per driver (e.g. ttySC0 >> >> > instead of ttyS0). >> >> > >> >> > There has been discussion in the past about changing this to let all >> >> > drivers use the same namespace, but it's not yet clear to me how we'd do >> >> > this in a 100% backwards compatible way. Maybe it's best left to udev to >> >> > figure out the driver independent name, but then we definitely should use >> >> > the alias for that name. >> >> This discussion has come up in just the last month or so. >> >> My opinion is device name numbering should start at 0 with 0 being the >> preferred console device. > > That's completely different to everything I've heard and seen so far ;) > > For specifying the console we have the linux,stdout-path property in the > chosen node. My preferred console may not be a serial port at all in > which case I would end up with a serial0 = &lcd0 alias. Many > devicetrees specify aliases for i2c/spi/mmc controllers aswell. Should > they order their i2c controllers in the order of preference now? I was only referring to serial consoles for this discussion. I don't think expanding aliases usage beyond serial ports is a good thing. It may work for fixed h/w, but it won't for hotplug cases. This naming issue has been solved in other ways for other devices: udev persistent net rules, uuid for disks, etc. It needs to be solved for serial devices. > Most dtsi files in the kernel specify a SoC specific order of aliases > and I think this makes the most sense. I agree with Arnd here. If we are going to care about the name, it should be something that makes sense to the user of a board, not the SOC. Of course, if a board has a serial port labeled "Debug port" or something, that doesn't tell you the name or index either. Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
