Hi Lukas,

struct uart_8250_port contains mcr_mask and mcr_force members whose
sole purpose is to work around an alpha-specific quirk.  This code
doesn't belong in the core where it is executed by everyone else,
so move it to a proper ->set_mctrl callback which is used on alpha only.

The alpha-specific quirk was introduced in January 1995:
https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/diff/drivers/char/serial.c?h=1.1.83

The members in struct uart_8250_port were added in 2002:
https://git.kernel.org/history/history/c/4524aad27854

The quirk applies to non-PCI alphas and arch/alpha/Kconfig specifies
"select FORCE_PCI if !ALPHA_JENSEN".  So apparently the only affected
machine is the EISA-based Jensen that Linus was working on back then:
https://lore.kernel.org/all/CAHk-=wj1JWZ3sCrGz16nxEj7=0O+srMg6Ah3iPTDXSPKEws_SA@mail.gmail.com/ (local)

Up until now the quirk is not applied unless CONFIG_PCI is disabled.
If users forget to do that, the serial ports aren't usable on Jensen
and the machine may not boot in the first place.  Avoid by confining
the quirk to CONFIG_ALPHA_JENSEN instead.

Wouldn't that mean that you can't use a generic Alpha kernel on the Jensen
anymore? CONFIG_ALPHA_JENSEN is only set if you specifically select the
Jensen as target, not when you build a generic kernel. That would be a step
back in my opinion, as the Debian generic kernel from debian-ports did
as least boot up on real hardware and the serial console worked just fine
[granted, the EISA cards were not detected, even after support for it
got enabled, but that's another case of worms].

Unfortunately I still can't boot my Jensen with a self-build kernel (that
it's the only Alpha without netboot makes it only harder), so
I can't even test your patch, but my plan is to get it booting over
my xmas vacation :-)

CU,
Uli
-- 
Dipl. Inf. Ulrich Teichert|e-mail: Ulrich.Teichert@gmx.de | Listening to:
Stormweg 24               |Eat Lipstick: Dirty Little Secret, The Baboon Show:
24539 Neumuenster, Germany|Work Work Work, The Bellrays: Bad Reaction