revert "x86, serial: convert legacy COM ports to platform devices"

Revert 7e92b4fc345f5b6f57585fbe5ffdb0f24d7c9b26.  It broke Sébastien Dugué's
machine and Jeff said (persuasively)

  This seems like it will break decades-long-working stuff, in favor of
  breaking new ground in our favorite area, "trusting the BIOS."

  It's just not worth it for serial ports, IMO.  Serial ports are something
  that just shouldn't break at this late stage in the game.  My new Intel
  platform boxes don't even have serial ports, so I question the value of
  messing with serial port probing even more...  because...  just wait a year,
  and your box won't have a serial port either!  :)

  I certainly don't object to the use of platform devices (or isa_driver),
  but the probe change seems questionable.  That's sorta analagous to
  rewriting the floppy driver probe routine.  Sure you could do it...  but why
  risk all that damage and go through debugging all over again?

  It seems clear from this report that we cannot, should not, trust BIOS for
  something (a) so simple and (b) that has been working for over a decade.

Much discussion ensued and we've decided to have another go at all of this.

Cc: Sébastien Dugué <sebastien.dugue@bull.net>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Adam Belay <ambx1@neo.rr.com>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Jeff Garzik <jeff@garzik.org>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
Cc: Sascha Sommer <saschasommer@freenet.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 5 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index d763ebe11afe..efdb42fd3fb8 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -864,11 +864,6 @@ and is between 256 and 4096 characters. It is defined in the file
         lasi=           [HW,SCSI] PARISC LASI driver for the 53c700 chip
                         Format: addr:<io>,irq:<irq>
 
-        legacy_serial.force [HW,X86-32,X86-64]
-                        Probe for COM ports at legacy addresses even
-                        if PNPBIOS or ACPI should describe them.  This
-                        is for working around firmware defects.
-
         load_ramdisk=   [RAM] List of ramdisks to load from floppy
                         See Documentation/ramdisk.txt.