by the number of available isochronous DMA contexts and active quirks
which is occasionally useful information.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

This bug was present in firewire-ohci since day one:  The number of
available isochronous receive DMA contexts was mixed up with that of
available isochronous transmit DMA contexts.

This is harmless on a few chips which offer the same number of contexts
in both directions, but most chips nowadays implement only the standard
minimum of 4 IR contexts, but 8 IT contexts.  If a user attempted to run
a lot of IR contexts at once, results with more than four were therefore
unpredictable.  I suppose the controller would simply refuse to start
DMA of any unimplemented context.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

This way, we can advise users of precompiled kernel packages to test
existing quirk fixes on chips which have not been listed yet, without
them having to build a kernel from source.

Note, to use this feature on a machine with more than one controller,
steps like these are necessary:
# lspci | grep 1394
# ls /sys/bus/pci/drivers/firewire_ohci/
# echo -n "0000:03:02.0" > /sys/bus/pci/drivers/firewire_ohci/unbind
# echo 2 > /sys/module/firewire_ohci/parameters/quirks
# echo -n "0000:03:02.0" > /sys/bus/pci/drivers/firewire_ohci/bind
# echo 0 > /sys/module/firewire_ohci/parameters/quirks

The parameter can also be used to switch off quirk flags that were
hardwired into firewire-ohci's quirks table.  Simply specify a non-zero
quirks value but without any known flags, e.g. 0x100.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

We don't have a lot of quirks to take into account (especially since
dual-buffer IR is out of the picture), but still, a table-based approach
is more organized than a series of if () clauses.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

The config_rom struct members are only accessed during relatively
infrequent self-ID-complete interrupts and only if the local config ROM
was changed, while the ar_, at_, ir_, it_ members are used very
frequently during I/O.  Hence move the config_rom members further down.

More importantly, make the huge self_id_buffer member the last one; this
is only accessed in self-ID-complete interrupts.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

This code was no longer used since 2.6.33, "firewire: ohci: always use
packet-per-buffer mode for isochronous reception" commit 090699c0.  If
anybody needs this code in the future for special purposes, it can be
brought back in.  But it must not be re-enabled by default; drivers
(kernelspace or userspace drivers) should only get this mode if they
explicitly request it.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

The current implementation of Bus_Time read access was buggy since it
did not ensure that Bus_Time.second_count_hi and second_count_lo came
from the same 128 seconds period.

Reported-by: Håkan Johansson <f96hajo@chalmers.se>

Instead of a fix, remove Bus_Time register support altogether.  The spec
requires all cycle master capable nodes to implement this (all Linux
nodes are cycle master capable) while it also says that it "may" be
initialized by the bus manager or by the IRM standing in for a bus
manager.  (Neither Linux' firewire-core nor ieee1394 nodemgr implement
this.)

Since we cannot rely on Bus_Time having been initialized by a bus
manager, it is better to return an error instead of a nonsensical value
on a read request to Bus_Time.

Alternatively, we could fix the Bus_Time read integrity bug _and_
implement (a) cycle master's write support of the register as well as
(b) bus manager's Bus_Time initialization service, i.e. preservation of
the Bus_Time when the cycle master node of a bus changes.  However, that
would be quite some code for a feature that is unreliable to begin with
and very likely unused in practice.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

ohci:  Break out of the retry loop if too many attempts were necessary.
This may theoretically happen if the chip is fatally defective or if the
get_cycle_timer ioctl was performed after a CardBus controller was
ejected.

Also micro-optimize the loop by re-using the last two register reads in
the next iteration, remove a questionable inline keyword, and shuffle a
comment around.

core:  ioctl_get_cycle_timer() is always called with interrupts on,
therefore local_irq_save() can be replaced by local_irq_disable().
Disabled local IRQs imply disabled preemption, hence preempt_disable()
can be removed.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

Discussed in "read_cycle_timer backwards for sub-cycle 0000, 0001",
http://thread.gmane.org/gmane.linux.kernel.firewire.devel/13704

Known bad controllers:
  ALi M5271, listed by lspci as M5253 [10b9:5253]
  NEC OrangeLink [1033:00cd] (rev 03)
  NEC uPD72874 [1033:00f2] (rev 01)
  VIA VT6306 [1106:3044] (rev 46)
  VIA VT6308P, listed by lspci as rev c0

Reported-by: Pieter Palmers <pieterp@joow.be>
Reported-by: Håkan Johansson <f96hajo@chalmers.se>
Reported-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>