Hi, How can we move forward here? On Thu, Jun 26, 2014 at 1:02 PM, Tomasz Figa <t.figa@xxxxxxxxxxx> wrote: > - basically Samsung UART already has its own namespace (ttySAC) and the > order inside it is well-defined - instance ID shall be the hardware > instance number as specified by documentation. The ports vary in certain > aspects and the ID is important knowledge of the driver. The problem > here was broken implementation of assigning IDs based on probe order, > which worked only because on all Exynos platforms all ports have been > always registered (which we want to change now and keep unused ones > "disabled" in DT), Yes, the kernel help text documents this quite well: config SERIAL_SAMSUNG tristate "Samsung SoC serial support" depends on PLAT_SAMSUNG select SERIAL_CORE help Support for the on-chip UARTs on the Samsung S3C24XX series CPUs, providing /dev/ttySAC0, 1 and 2 (note, some machines may not provide all of these ports, depending on how the serial port pins are configured. > - we already have a lot of userspace depending on the aforementioned > ttySAC namespace and proper ordering of instances there. While I believe > the proper solution as of today would be to go back to standard ttyS > namespace and make userspace use a smarter way of identifying the > instances (e.g. by path or id, as you suggested), I don't think this > will make anyone's life easier with current assumptions, I like the sound of going to the standard ttyS notation and only providing ports for ones that exist, but is this userspace-visible naming change OK? You could argue that userspace that relies on fixed device paths is a bit broken, but that argument would be a bit cloudy given the kernel documentation for the ttySAC devices above. > - correct me if I'm wrong, but I don't think the > /dev/serial/by-{path,id} would be handled in kernel's console= parameter. That's right, that problem is left to the user, but at least we'd be consistent with other SoCs (and open to generic solutions to that inconvenience). Daniel -- 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