Known problems and limitations for the 3.1.27 PCMCIA release
============================================================

Bug summaries:

o CardBus devices with 2.0.* kernels are not recommended
o PCI interrupt routing issues for CardBus bridges on some systems
o O2Micro and ToPIC CardBus bridge configuration problems
o On the Sony VAIO PCG-N505VE, interrupts break after a suspend
o SCSI drivers are not hot swap safe
o Iomega Clik! drives require a kernel patch
o Token ring memory allocation issues
o Interrupt lossage with Megahertz multifunction cards
o The aic7xxx/apa1480_cb driver misbehaves if the cable is detached
o Ositech Jack of Diamonds firmware issue
o Serial interrupt sharing bug in certain 2.2.*, 2.3.* kernels
o aha152x interrupt bug in certain 2.2.* kernels
o IDE driver shutdown bug in certain 2.2.*, 2.3.* kernels
o Tedious IDE probes for nonexistent slave devices
o IDE driver does not share PCI interrupts properly
o SuSE 6.4 IDE driver problem
o Multicast filter problem with xirc2ps_cs driver

Bug details:

o Use of CardBus cards with 2.0.* kernels is discouraged.  It may work
  on some systems, but not on others, due to PCI BIOS limitations.
  Also, it is harder to diagnose problems, because /proc/bus/pccard is
  not available with these kernels.

o With some PCI host bridges, the PCMCIA subsystem is not able to
  determine the PCI interrupt routing for CardBus bridges.  For some
  types of CardBus bridges, this means that we can't configure
  interrupts for CardBus cards at all.  When the PCMCIA drivers are
  loaded, they may complain about an "unknown interrupt router".

  Prognosis: see the discussion in the PCMCIA-HOWTO.

o Interrupt routing on O2Micro CardBus bridges seems to have problems.
  Toshiba ToPIC97 bridges also seem to have problems, particularly
  with Cardbus cards.

  Prognosis: I think the O2Micro problems should now be fixed.  For
  the ToPIC problem, Toshiba does not seem willing and/or able to
  provide adequate help, so I've mostly given up on it.  For both the
  O2Micro and ToPIC problems, fixes would require someone with device
  driver experience and the relevant hardware to work on it: data
  sheets are available, and I can make suggestions of things to try,
  but I can't debug the problems by email.

  With ToPIC chipsets, some systems seem to work better if the bridge
  mode is changed to either "PCIC" or "CardBus", rather than "Auto",
  in the BIOS setup menu.

  In some cases, ToPIC chipsets generate bogus eject/insert sequences
  when a card is first powered up.  It may be useful to increase the
  vcc_settle and/or setup_time parameters for the pcmcia_core module
  to prevent this.

o On the Sony VAIO PCG-N505VE, after a suspend, no interrupts are
  delivered by the CardBus bridge until the system is rebooted.

  Prognosis: I've spent a lot of time trying to track this down, but
  I'm completely stumped.  The PCMCIA drivers appear to restore the
  state of the CardBus bridge correctly, and the PCI interrupt router
  is also configured properly.  But no interrupts get through.

o All of the SCSI drivers, and most of the CardBus drivers, do not
  implement suspend/resume handling.  The only workaround now is to
  eject these cards (or do "cardctl eject") before suspending.
  
  Prognosis: CardBus Network cards will probably be fixed eventually,
  but it has not been a high priority.  SCSI drivers are less likely
  to be fixed since we're more dependent on kernel code.

o The Iomega Clik! drive is incompatible with the kernel ide-floppy
  driver.  Kernel updates for 2.2 and 2.4 kernels are available at
  http://paulbristow.net/linux/clik.html.

o The token ring driver tweaks a problem in the memory management
  code.  To work around the problem, remove all high memory windows
  from /etc/pcmcia/config.opts.  The driver is also completely broken
  for late 2.1 and early 2.2 kernels.  A fix is in 2.2.7.

o Megahertz EM1144, EM3288, and EM3336 cards drop interrupts if the
  modem and ethernet are used simultaneously.
  
  Prognosis: Unlikely to be fixed, since these cards are old and we
  are unlikely to ever get more complete tech info.

o The kernel aic7xxx driver, which is linked into the apa1480_cb
  driver, can generate spurious interrupts when a card is initialized,
  which can cause system lockups.  This will usually happen if the
  card is inserted with no SCSI cable attached.

  Prognosis: I've sent a patch to the driver maintainer.  The problem
  can be mostly mitigated by disabling use of PCI interrupts for
  CardBus cards, by setting PCIC_OPTS="pci_int=0".  This setting does
  not work on some newer laptops; in those cases, you'll have to wait
  for a kernel update to fix the problem.

o Some Ositech Jack of Diamonds 33.6K modem/ethernet cards don't work
  because of a firmware issue.  With these cards, the smc91c92_cs
  driver reports "Bad chip signature".

  A DOS program to update the card firmware to v8.1B is available from
  Ositech's web site at ftp://www.ositech.com/pub/jod/JDCEL422.EXE

o The 2.2.*/2.3.* serial driver had a bug that interfered with
  interrupt sharing for multifunction cards.  The effect is that
  opening a serial port on a multifunction card fails, giving an IO
  error.  It was fixed in 2.2.11 and 2.3.9.

  The bug can be fixed by editing linux/drivers/char/serial.c and
  changing each use of IRQ_T(info) to IRQ_T(state).

o The kernel aha152x driver, used for Adaptec 16-bit SCSI adapters,
  had a PCMCIA compatibility problem in 2.2.* that was fixed in 2.2.9.
  The effect was that interrupts were ignored, unless the card
  happened to be configured for irq 9..12.

  Either upgrade to a 2.2.9 or later kernel, or if you have an
  appropriate interrupt available, add to /etc/pcmcia/config.opts:

    module "aha152x_cs" opts "irq_list=9,10,11,12"

o The kernel IDE driver had a bug that causes shutdown of some PCMCIA
  IDE cards to cause a kernel trap.  It was introduced in 2.2.9/2.3.1
  and fixed in 2.2.10/2.3.4.

o For some ATA/IDE devices, the IDE driver will lock up the system for
  up to 15 seconds while probing for (non-existent) slave devices.

  I've told the IDE maintainer about the issue and it is just a matter
  of getting the kernel driver updated.  There are two aspects to the
  fix; one is to improve automatic detection of flash memory cards,
  and the other is to change the probe to sleep instead of freezing
  the system during the probe.  The 2.4 driver is fixed.

o The linux IDE driver generates spurious interrupts when it probes
  for new devices.  This is ok at boot time because the IDE probe runs
  before almost all other drivers.  But it causes lockups if the probe
  is done when another driver is using the same PCI interrupt.  This
  happens when the PCMCIA subsystem is configured to use only PCI
  interrupts for card status changes as well as card interrupts.

  Prognosis: the IDE device probe needs to be rewritten; I don't know
  when that might happen.  In some situations, you can work around the
  issue by using startup options like:

    PCIC_OPTS="irq_mode=0 pci_csc=0"

  which will prevent the i82365 driver from sharing the PCI interrupt
  for monitoring card insert/eject events; this will not help if other
  PCI devices also need to share.

o The SuSE 6.4 version of the 2.2.14 kernel has a broken IDE probe
  that messes up at least some PCMCIA devices.  The result is that
  the ide_cs driver reports "ide_register(...) failed".

  Prognosis: substitute drivers/block/ide-probe.c from SuSE's 2.2.13
  kernel or from a virgin 2.2.14 source tree.

o Multicast filter problem with xirc2ps_cs driver

I have some reports that multicast filtering doesn't work properly in
the xirc2ps_cs driver.  I have not investigated further.
