On Thu, Jul 20, 2023 at 07:13:19AM +0300, Tony Lindgren wrote: > * Andy Shevchenko <andriy.shevchenko@xxxxxxxxx> [230719 13:59]: > > On Wed, Jul 19, 2023 at 08:43:21AM +0300, Tony Lindgren wrote: > > > * Andy Shevchenko <andriy.shevchenko@xxxxxxxxx> [230719 05:34]: > > > > On Wed, Jul 19, 2023 at 08:16:11AM +0300, Tony Lindgren wrote: ... > > > > > And with this, we can add /dev/serial/by-id symlinks to the serial port > > > > > device instances so we can start using serial core port addressing in > > > > > addition to the legacy ttyS naming. > > > > > > > > > > The naming we can use is dev_name:0.0 where 0.0 are the serial core > > > > > controller id and port id, so for the ttyS0 example above the naming > > > > > would be 00:04.0:0.0. > > > > > > > > This is interesting idea. But any hint why it can be useful? > > > > > > If you have lots of serial ports and we are stuck with adding aliases > > > for the ports in the dts files where the ttyS naming and ordering does > > > not really help or may not necessarily make sense if the ports are on > > > different buses or domains. With CONFIG_SERIAL_8250_RUNTIME_UARTS=4, > > > the ttyS naming is only needed for the legacy ports really. > > > > I see. Does it fix the long standing issue with ttyS enumeration (on x86 > > at least) when depending on the presence of the legacy ports the HSUART > > (high speed) can preempt the legacy placeholders (ttyS0..ttyS3)? > > > > To me sounds like it may very well do fix it and I would be glad to see that > > in the commit message (as selling point) and in documentation. > > It won't affect how ttyS0..ttyS3 get assigned, but it helps finding your > HSUART instance with DEVNAME:0.0 style addressing. So you don't need to > care what ttyS number the port has. If you have such a test case maybe give > it a try. Exactly, the problem (currently) is, that depending on the BIOS settings the kernel can't use the same command line and this is quite a PITA for our customers! As far as we can specify hardware (path) to the console, it will be so cool and hopefully solves this very long standing issue. -- With Best Regards, Andy Shevchenko
