On Wednesday 21 October 2015 18:09:33 Masahiro Yamada wrote: > Hi Arnd, > > > 2015-10-21 17:57 GMT+09:00 Arnd Bergmann <arnd@xxxxxxxx>: > > On Wednesday 21 October 2015 17:21:07 Masahiro Yamada wrote: > >> Hi. > >> > >> > >> > >> > >> I think there are three places where console could be enabled. > >> > >> [1] earlycon > >> > >> Each driver entry is declared with > >> EARLYCON_DECLARE() or OF_EARLYCON_DECLARE() > >> > >> > >> > >> [2] console_init() > >> > >> Each entry is declared with console_initcall() > >> > >> > >> > >> [3] when driver is probed > >> The console is usually enabled at this point > >> unless some special treatment is done. > >> > >> > >> > >> > >> My question is about [2]. > >> > >> I am using 8250-ish UART device. > >> > >> > >> I noticed univ8250_console_match() and univ8250_console_setup() > >> always fail at the point of [2] unless early_serial_setup() has been > >> called in advance; > >> however, it looks like early_serial_setup() is only used for old platforms. > >> > >> So, console cannot be enabled at [2] for modern platforms. > >> > >> > >> My questions are: > >> > >> - Given that earlycon can be now available for major architectures such ARM, > >> [2] will be deprecated at some point in the future? > >> > >> - I am implementing earlycon for my own UART driver. > >> Is it meaningless to implement console_initcall() as well as earlycon? > > > > I would still do both. We don't enable earlycon by default at the moment, > > and I'd say things should remain working with just console_initcall(). > > > > How closely related to 8250 is your hardware? If it's not all that different, > > you should probably reuse the existing driver. > > > Very close. > It is already in the mainline. > > drivers/tty/serial/8250/8250_uniphier.c > > The core parts are shared with 8250_core.c Ok, but I guess no close enough that it makes sense to use drivers/serial/of_serial.c > I am trying to implement OF_EARLYCON_DECLARE() for that. > > I was just wondering if console_initcall() should work as well. > > > As I said, I noticed the console_initcall() in 8250_core.c > only works on very limited platforms. It works with all those that use of_serial.c, right? I think they are the majority. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
