On Sun, Jan 31, 2021 at 03:47:42PM +0000, Måns Rullgård wrote: > Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> writes: > > > On Sun, Jan 31, 2021 at 01:18:47PM +0000, Måns Rullgård wrote: > >> Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> writes: > >> > >> > On Thu, Jan 28, 2021 at 05:22:44PM +0000, Mans Rullgard wrote: > >> >> On systems that do not have the traditional PC ISA serial ports, the > >> >> 8250 driver still creates non-functional device nodes. This change > >> >> makes only ports that actually exist (PCI, DT, ...) get device nodes. > >> >> > >> >> Signed-off-by: Mans Rullgard <mans@xxxxxxxxx> > >> >> --- > >> >> drivers/tty/serial/8250/8250_core.c | 26 ++++++++++++++++++++------ > >> >> drivers/tty/serial/8250/Kconfig | 5 +++++ > >> >> 2 files changed, 25 insertions(+), 6 deletions(-) > >> >> > >> >> diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c > >> >> index cae61d1ebec5..49695dd3677c 100644 > >> >> --- a/drivers/tty/serial/8250/8250_core.c > >> >> +++ b/drivers/tty/serial/8250/8250_core.c > >> >> @@ -555,6 +555,7 @@ static void __init serial8250_isa_init_ports(void) > >> >> } > >> >> } > >> >> > >> >> +#ifdef CONFIG_SERIAL_8250_ISA > >> > > >> > This is just making a mess of the code. > >> > >> It was already a mess. > > > > True, but don't make it a worse one please. > > > >> > >> > To do this right, pull the isa code out into a separate file and put > >> > the #ifdef in a .h file, so we can properly maintain and support this > >> > code over time. This change as-is is not going to make that any > >> > easier :( > >> > >> I might put in that effort if there's a reasonable chance this change > >> will be accepted. If it's going to be rejected regardless, I'd rather > >> not waste my time. > >> > >> >> +config SERIAL_8250_ISA > >> >> + bool "8250/16550 ISA device support" if EXPERT > >> > > >> > So, no one will set this? > >> > >> I followed the pattern of the existing SERIAL_8250_PNP option. Was that > >> a mistake? How would you prefer it? > > > > I don't know, I'm just asking. > > > >> > What userspace visable change will be caused by this? > >> > >> There won't be /dev/ttyS devices for ports that don't exist. > >> > >> > Will ports get renumbered? > >> > >> Not if they had predictable numbers to begin with. > > > > So that would be "yes"? If so, obviously we couldn't take this, right? > > On a Beaglebone Black based system with some of the UARTs enabled, those > keep their numbers such that e.g. ttyS0, ttyS1, and ttyS4 show up in > /dev while ttyS2 and ttyS3 do not since they don't correspond to any > (enabled) ports. > > If any of the very many variants of this driver do not assign fixed > numbers, those would possibly be renumbered. Should that be the case, > the numbering was never guaranteed to begin with, so I fail to see any > problem. Ok, if that's the case, then yes, a cleaned up version of this patch would be nice, thanks! greg k-h
