Each host instance now has it's own work queue so the main() work item can
sleep when necessary. That means we can use a simple work item rather than
a delayed work item. This brings NCR5380.c closer to atari_NCR5380.c.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
When there is a queued command and no connected command, NCR5380_select()
is called and arbitration begins. The chip waits for BUS FREE once the
MR_ARBITRATE bit in the mode register is enabled. That means there is
no need to wait for BUS FREE after disconnecting.
There is presently no polling for BUS FREE after sending an ABORT or
other message that might lead to disconnection. It only happens after
COMMAND COMPLETE or DISCONNECT messages, which seems inconsistent.
Remove the polling for !BSY in the COMMAND COMPLETE and DISCONNECT
cases.
BTW, the comments say "avoid nasty timeouts" and perhaps BUS FREE polling
was somehow helpful back in Linux v0.99.14u, when it was introduced.
The relevant timeout is presently 1 second (for bus arbitration).
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Allow target selection to fail with a timeout instead of waiting in
infinite loops. This gets rid of the unused NCR_TIMEOUT macro, it is more
defensive and has proved helpful in debugging.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Use timeouts in do_abort() in atari_NCR5380.c instead of infinite loops.
Also fix the kernel-doc comment. Keep the two core driver forks in sync.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
NCR5380_poll_politely() returns either 0 (success) or -ETIMEDOUT. However,
in do_abort(), the return value is incorrectly taken to be the status
register value. This means that the bus is put into DATA OUT phase instead
of MESSAGE OUT. Fix this.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
NCR5380_poll_politely() never returns -1. That means do_abort() can fail
to handle a timeout after waiting for the target to negate REQ. Fix this
and cleanup other NCR5380_poll_politely() call sites.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
MESSAGE REJECT does not imply DISCONNECT: the target is about to enter
MESSAGE IN or MESSAGE OUT phase.
This bug fix comes from atari_NCR5380.c. Unfortunately it never made it
into the original NCR5380.c core driver.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Some old drivers partially implemented support for linked commands using
a "proposed" next_link pointer in struct scsi_cmnd that never actually
existed. Remove this code.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Remove the DEF_SCSI_QCMD macro (already removed from atari_NCR5380.c). The
lock provided by DEF_SCSI_QCMD is only needed for queue data structures.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
According to the SCSI-2 draft revision 10L, atari_NCR5380.c is correct
when it says that the phase lines are valid up until ACK is negated
following the transmission of the last byte in MESSAGE IN phase. This is
true for all information transfer phases, from target to initiator.
Sample the phase bits in STATUS_REG so that NCR5380_transfer_pio() can
return the correct result. The return value is presently unused (perhaps
because of bugs like this) but this change at least fixes the caller's
phase variable, which is passed by reference.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
The atari_NCR5380.c and NCR5380.c core drivers differ in their handling of
target disconnection. This is partly because atari_NCR5380.c had all of
the polling and sleeping removed to become entirely interrupt-driven, and
it is partly because of damage done to NCR5380.c after atari_NCR5380.c was
forked. See commit 37cd23b44929 ("Linux 2.1.105") in history/history.git.
The polling changes that were made in v2.1.105 are questionable at best:
if REQ is not already asserted when NCR5380_transfer_pio() is invoked, and
if the expected phase is DATA IN or DATA OUT, the function will schedule
main() to execute after USLEEP_SLEEP jiffies and then return. The problems
here are the expected REQ timing and the sleep interval*. Avoid this issue
by using NCR5380_poll_politely() instead of scheduling main().
The atari_NCR5380.c core driver requires the use of the chip interrupt and
always permits target disconnection. It sets the cmd->device->disconnect
flag when a device disconnects, but never tests this flag.
The NCR5380.c core driver permits disconnection only when
instance->irq != NO_IRQ. It sets the cmd->device->disconnect flag when
a device disconnects and it tests this flag in a couple of places:
1. During NCR5380_information_transfer(), following COMMAND OUT phase,
if !cmd->device->disconnect, the initiator will take a guess as to
whether or not the target will then choose to go to MESSAGE IN phase
and disconnect. If the driver guesses "yes", it will schedule main()
to execute after USLEEP_SLEEP jiffies and then return there.
Unfortunately the driver may guess "yes" even after it has denied
the target the disconnection privilege. When the target does not
disconnect, the sleep can be beneficial, assuming the sleep interval
is appropriate (mostly it is not*).
And even if the driver guesses "yes" correctly, and the target would
then disconnect, the driver still has to go through the MESSAGE IN
phase in order to get to BUS FREE phase. The main loop can do nothing
useful until BUS FREE, and sleeping just delays the phase transition.
2. If !cmd->device->disconnect and REQ is not already asserted when
NCR5380_information_transfer() is invoked, the function polls for REQ
for USLEEP_POLL jiffies. If REQ is not asserted, it then schedules
main() to execute after USLEEP_SLEEP jiffies and returns.
The idea is apparently to yeild the CPU while waiting for REQ.
This is conditional upon !cmd->device->disconnect, but there seems
to be no rhyme or reason for that. For example, the flag may be
unset because disconnection privilege was denied because the driver
has no IRQ. Or the flag may be unset because the device has never
needed to disconnect before. Or if the flag is set, disconnection
may have no relevance to the present bus phase.
Another deficiency of the existing algorithm is as follows. When the
driver has no IRQ, it prevents disconnection, and generally polls and
sleeps more than it would normally. Now, if the driver is going to poll
anyway, why not allow the target to disconnect? That way the driver can do
something useful with the bus instead of polling unproductively!
Avoid this pointless latency, complexity and guesswork by using
NCR5380_poll_politely() instead of scheduling main().
* For g_NCR5380, the time intervals for USLEEP_SLEEP and USLEEP_POLL are
200 ms and 10 ms, respectively. They are 20 ms and 200 ms respectively
for the other NCR5380 drivers. There doesn't seem to be any reason for
this discrepancy. The timing seems to have no relation to the type of
adapter. Bizarrely, the timing in g_NCR5380 seems to relate only to one
particular type of target device. This patch attempts to solve the
problem for all NCR5380 drivers and all target devices.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Follow the example of the atari_NCR5380.c core driver and adopt the
NCR5380_dma_xfer_len() hook. Implement NCR5380_dma_xfer_len() for dtc.c
and g_NCR5380.c to take care of the limitations of these cards. Keep the
default for drivers using PSEUDO_DMA.
Eliminate the unused macro LIMIT_TRANSFERSIZE.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
If NCR5380_select() returns -1, it means arbitration was lost or selection
failed and should be retried. If the main loop simply terminates when there
are still commands on the issue queue, they will remain queued until they
expire.
Fix this by clearing the 'done' flag after selection failure or lost
arbitration.
The "else break" clause in NCR5380_main() that gets removed here appears
to be a vestige of a long-gone loop that iterated over host instances.
See commit 491447e1fcff ("[PATCH] next NCR5380 updates") in
history/history.git.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux v2.1.105 changed the algorithm for polling for the BSY signal
in NCR5380_select() and NCR5380_main().
Presently, this code has a bug. Back then, NCR5380_set_timer(hostdata, 1)
meant reschedule main() after sleeping for 10 ms. Repeated 25 times this
provided the recommended 250 ms selection time-out delay. This got broken
when HZ became configurable.
We could fix this but there's no need to reschedule the main loop. This
BSY polling presently happens when the NCR5380_main() work queue item
calls NCR5380_select(), which in turn schedules NCR5380_main(), which
calls NCR5380_select() again, and so on.
This algorithm is a deviation from the simpler one in atari_NCR5380.c.
The extra complexity and state is pointless. There's no reason to
stop selection half-way and return to to the main loop when the main
loop can do nothing useful until selection completes.
So just poll for BSY. We can sleep while polling now that we have a
suitable workqueue.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
When in process context, sleep during polling if doing so won't add
significant latency. In interrupt context or if the lock is held, poll
briefly then give up. Keep both core drivers in sync.
Calibrate busy-wait iterations to allow for variation in chip register
access times between different 5380 hardware implementations.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Allocate a work queue that will permit busy waiting and sleeping. This
means NCR5380_init() can potentially fail, so add this error path.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux 2.1.105 introduced the USLEEP_WAITLONG delay, apparently "needed for
Mustek scanners". It is intended to stall the issue queue for 5 seconds.
There are a number of problems with this.
1. Only g_NCR5380 enables the delay, which implies that the other five
drivers using the NCR5380.c core driver remain incompatible with
Mustek scanners.
2. The delay is not implemented by atari_NCR5380.c, which is problematic
for re-unifying the two core driver forks.
3. The delay is implemented using NCR5380_set_timer() which makes it
unreliable. A new command queued by the mid-layer cancels the delay.
4. The delay is applied indiscriminately in several situations in which
NCR5380_select() returns -1. These are-- reselection by the target,
failure of the target to assert BSY, and failure of the target to
assert REQ. It's clear from the comments that USLEEP_WAITLONG is not
relevant to the reselection case. And reportedly, these scanners do
not disconnect.
5. atari_NCR5380.c was forked before Linux 2.1.105, so it was spared some
of the damage done to NCR5380.c. In this case, the atari_NCR5380.c core
driver was more standard-compliant and may not have needed any
workaround like the USLEEP_WAITLONG kludge. The compliance issue was
addressed in the previous patch.
If these scanners still don't work, we need a better solution. Retrying
selection until EH aborts a command offers equivalent robustness. Bugs in
the existing driver prevent EH working correctly but this is addressed in
a subsequent patch. Remove USLEEP_WAITLONG.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
NCR5380.c is not compliant with the SCSI-2 standard (at least, not with
the draft revision 10L that I have to refer to). The selection algorithm
in atari_NCR5380.c is correct, so use that.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
If a target disappears from the SCSI bus, NCR5380_select() may
subsequently fail with a time-out. In this situation, scsi_done is
called and NCR5380_select() returns 0. Both hostdata->connected and
hostdata->selecting are NULL and the main loop should proceed with
the next command in the issue queue. Clarify this logic.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Remove the restart_select and targets_present variables introduced in
Linux v1.1.38. The former was used only for a questionable debug printk
and the latter "so we can call a select failure a retryable condition".
Well, retrying select failure in general is a different problem to a
target that doesn't assert BSY. We need to handle these two cases
differently; the latter case can be left to the SCSI ML.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
The "failed" label in NCR5380_select() is not helpful. Some failures
return 0, others -1. Use return instead of goto to improve clarity and
brevity, like atari_NCR5380.c does. Fix the relevant comments.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Remove the duplicate write to the Select Enable Register that appeared
in v1.1.38.
Also remove the redundant write to Initiator Command Register prior to
calling do_abort().
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
The aborted flag was introduced in v1.1.38 but never used. Remove it.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Make use of do_reset() in the bus reset handler in atari_NCR5380.c. The
version in NCR5380.c already does so. Keep them in sync.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
The atari_NCR5380.c core driver now takes care of bus reset upon driver
initialization if required (same as NCR5380.c). Move the Toshiba CD-ROM
support into the core driver, enabled with a host flag, so that all
NCR5380 drivers can make use of it.
Drop the RESET_BOOT macros and the ATARI_SCSI_RESET_BOOT and
ATARI_SCSI_TOSHIBA_DELAY Kconfig symbols, which are now redundant.
Remove the atari_scsi_reset_boot(), mac_scsi_reset_boot() and
sun3_scsi_reset_boot() routines. None of this duplicated code is needed
now that all drivers can use NCR5380_maybe_reset_bus().
This brings atari_scsi, mac_scsi and sun3_scsi into line with all of the
other NCR5380 drivers.
The bus reset may raise an interrupt. That would be new behaviour for
atari_scsi only when CONFIG_ATARI_SCSI_RESET_BOOT=n. The ST DMA interrupt
is not assigned to atari_scsi at this stage, so
CONFIG_ATARI_SCSI_RESET_BOOT=y may well be problematic already.
Regardless, do_reset() now raises and clears the interrupt within
local_irq_save/restore which should avoid problems.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Merge the bus reset code from NCR5380.c into atari_NCR5380.c. This allows
for removal of a lot of duplicated code conditional on the RESET_BOOT
macro (in the next patch).
The atari_NCR5380.c fork lacks the do_reset() and NCR5380_poll_politely()
routines from NCR5380.c, so introduce them. They are indispensible. Keep
the two implementations in sync.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Move board-specific code like this,
NCR5380_write(C400_CONTROL_STATUS_REG, CSR_BASE);
from the core driver to the board driver. Eliminate the NCR53C400 macro
from the core driver. Removal of all macros like this one will be
necessary in order to have one core driver that can support all kinds of
boards.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This patch splits the NCR5380_init() function into two parts, similar
to the scheme used with atari_NCR5380.c. This avoids two problems.
Firstly, NCR5380_init() may perform a bus reset, which would cause the
chip to assert IRQ. The chip is unable to mask its bus reset interrupt.
Drivers can't call request_irq() before calling NCR5380_init(), because
initialization must happen before the interrupt handler executes. If
driver initialization causes an interrupt it may be problematic on some
platforms. To avoid that, first move the bus reset code into
NCR5380_maybe_reset_bus().
Secondly, NCR5380_init() contains some board-specific interrupt setup code
for the NCR53C400 that does not belong in the core driver. In moving this
code, better not re-order interrupt initialization and bus reset. Again,
the solution is to move the bus reset code into NCR5380_maybe_reset_bus().
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This macro makes the code cryptic. Remove it.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
The NCR5380_local_declare and NCR5380_setup macros exist to define and
initialize a particular local variable, to provide the address of the
chip registers needed for the driver's implementation of its
NCR5380_read/write register access macros.
In cumana_1 and macscsi, these macros generate pointless code like this,
struct Scsi_Host *_instance;
_instance = instance;
In pas16, the use of NCR5380_read/write in pas16_hw_detect() requires that
the io_port local variable has been defined and initialized, but the
NCR5380_local_declare and NCR5380_setup macros can't be used for that
purpose because the Scsi_Host struct has not yet been instantiated.
Moreover, these macros were removed from atari_NCR5380.c long ago and
now they constitute yet another discrepancy between the two core driver
forks.
Remove these "optimizations".
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Instances of var * HZ / 1000 are replaced by msecs_to_jiffies(var).
In addition some timing constants that assumed HZ 100 were adjusted
to HZ independent settings based on review comments from Michael Schmitz
<schmitzmic@gmail.com> and review of the original drivers in 1.0.31 and
2.2.16.
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Acked-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Using seq_putc to print a single character saves at least a strlen()
call and a memory access, and may also give a small .text reduction.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Using seq_printf to print a simple string is a lot more expensive than
it needs to be, since seq_puts exists. Replace seq_printf with
seq_puts when possible.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The macro SPRINTF doesn't save a lot of typing or make the code more
readable, and depending on a specific identifier (m) in the
surrounding scope is generally frowned upon. Nuke it.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Convert Scsi_Cmnd to struct scsi_cmnd and drop the #include "scsi.h".
The sun3_NCR5380.c core driver already uses struct scsi_cmnd so converting
the other core drivers reduces the diff which makes them easier to unify.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The *_RELEASE macros don't tell me anything. In some cases the version in
the macro contradicts the version in the comments. Anyway, the Linux kernel
version is sufficient information. Remove these macros to improve readability.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Static variables from dtc.c and pas16.c should not appear in the core
NCR5380.c driver. Aside from being a layering issue this worsens the
divergence between the three core driver variants (atari_NCR5380.c and
sun3_NCR5380.c don't support PSEUDO_DMA) and it can mean multiple hosts
share the same counters.
Fix this by making the pseudo DMA spin counters in the core more generic.
This also avoids the abuse of the {DTC,PAS16}_PUBLIC_RELEASE macros, so
they can be removed.
oak.c doesn't use PDMA and hence it doesn't use the counters and hence it
needs no write_info() method. Remove it.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
If the host->info() method is not set, then host->name is used by default.
For atari_scsi, that is exactly the same text. So remove the redundant
info() method. Keep sun3_scsi.c in line with atari_scsi.
Some NCR5380 drivers return an empty string from the info() method
(arm/cumana_1.c arm/oak.c mac_scsi.c) while other drivers use the default
(dmx3191d dtc.c g_NCR5380.c pas16.c t128.c).
Implement a common info() method to replace a lot of duplicated code which
the various drivers use to announce the same information.
This replaces most of the (deprecated) show_info() output and all of the
NCR5380_print_info() output. This also eliminates a bunch of code in
g_NCR5380 which just duplicates functionality in the core driver.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The NCR5380_STATS option is only enabled by g_NCR5380 yet it adds
clutter to all three core drivers. The atari_NCR5380.c and sun3_NCR5380.c
core drivers have a slightly different implementation of the
NCR5380_STATS option.
Out of all ten NCR5380 drivers, only one of them (g_NCR5380) actually
has the code to report on the collected stats. Aside from being unreadable,
that code seems to be broken because there's no initialization of timebase.
sun3_NCR5380.c and atari_NCR5380.c have the timebase initialization but
lack the code to report the stats.
Remove all of this code to improve readability and reduce divergence
between the three core drivers.
This patch and the next one completely eliminate the PRINTP and ANDP
pre-processor abuse.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Oak scsi doesn't use any IRQ, but it sets irq = IRQ_NONE rather than
SCSI_IRQ_NONE. Problem is, the core NCR5380 driver expects SCSI_IRQ_NONE
if it is to issue IDENTIFY commands that prevent target disconnection.
And, as Geert points out, IRQ_NONE is part of enum irqreturn.
Other drivers, when they can't get an IRQ or can't use one, will set
host->irq = SCSI_IRQ_NONE (that is, 255). But when they exit they will
attempt to free IRQ 255 which was never requested.
Fix these bugs by using NO_IRQ in place of SCSI_IRQ_NONE and IRQ_NONE.
That means IRQ 0 is no longer probed by ISA drivers but I don't think
this matters.
Setting IRQ = 255 for these ISA drivers is understood to mean no IRQ.
This remains supported so as to avoid breaking existing ISA setups (which
can be difficult to get working) and because existing documentation
(SANE, TLDP etc) describes this usage for the ISA NCR5380 driver options.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Every NCR5380 driver sets AUTOSENSE so it need not be optional (and the
mid-layer expects it). Remove this redundant macro to improve readability.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Both atari_NCR5380.c and sun3_NCR5380.c core drivers #undef TAG_NONE and
then redefine it. But the original definition is unused because NCR5380.c
lacks support for tagged queueing. So just define it once.
The TAG_NEXT macro only appears in the arguments to NCR5380_select() calls.
But that routine doesn't use its tag argument as the tag was already
assigned in NCR5380_main(). So remove the unused argument and the macro.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Some macros are never evaluated (i.e. FOO, USLEEP, SCSI2 and USE_WRAPPER;
and in some drivers, NCR5380_intr and NCR5380_proc_info). DRIVER_SETUP
serves no purpose anymore. Remove these macro definitions.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The .eh_abort_handler needs to return SUCCESS, FAILED, or
FAST_IO_FAIL. So fixup all callers to adhere to this requirement.
Reviewed-by: Robert Elliott <elliott@hp.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Calling scsi_print_command should not be necessary during abort;
if the information is required one should enable scsi logging.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Robert Elliott <elliott@hp.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The SCSI standard defines 64-bit values for LUNs, and large arrays
employing large or hierarchical LUN numbers become more and more
common.
So update the linux SCSI stack to use 64-bit LUN numbers.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Ewan Milne <emilne@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
All three NCR5380 core driver implementations share the same NCR5380.h
header file so they need to agree on certain macro definitions.
The flag bit used by the NDEBUG_MERGING macro in atari_NCR5380 and
sun3_NCR5380 collides with the bit used by NDEBUG_LISTS.
Moreover, NDEBUG_ABORT appears in NCR5380.c so it should be defined in
NCR5380.h rather than in each of the many drivers using that core.
An undefined NDEBUG_ABORT macro caused compiler errors and led to dodgy
workarounds in the core driver that can now be removed.
(See commits f566a576bc and
185a7a1cd79b9891e3c17abdb103ba1c98d6ca7a.)
Move all of the NDEBUG_ABORT, NDEBUG_TAGS and NDEBUG_MERGING macro
definitions into NCR5380.h where all the other NDEBUG macros live.
Also, incorrect "#ifdef NDEBUG" becomes "#if NDEBUG" to fix the warning:
drivers/scsi/mac_scsi.c: At top level:
drivers/scsi/NCR5380.c:418: warning: 'NCR5380_print' defined but not used
drivers/scsi/NCR5380.c:459: warning: 'NCR5380_print_phase' defined but not used
The debugging code is now enabled when NDEBUG != 0.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Acked-by: Sam Creasey <sammy@sammy.net>
Signed-off-by: Christoph Hellwig <hch@lst.de>
There are three implementations of the core NCR5380 driver and three sets
of debugging macro definitions. And all three implementations use the
NCR5380.h header as well.
Two of the definitions of the dprintk macro accept a variable argument list
whereas the third does not. Standardize on the variable argument list.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Acked-by: Sam Creasey <sammy@sammy.net>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The change from cmd->target to cmd->device->id was apparently the purpose of
commit a7f251228390e87d86c5e3846f99a455517fdd8e in
kernel/git/tglx/history.git but some instances have been missed.
Also fix the "NDEBUG_LAST_WRITE_SENT" and "NDEBUG_ALL" typo's.
Also fix some format strings (%ul becomes %lu) that caused compiler warnings.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Acked-by: Sam Creasey <sammy@sammy.net>
Signed-off-by: Christoph Hellwig <hch@lst.de>
It's a NOOP since 2.6.35 and it will be removed one day.
[jejb: remove from missed arm scsi drivers]
Signed-off-by: Michael Opdenacker <michael.opdenacker@free-electrons.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
CONFIG_HOTPLUG is going away as an option. As a result, the __dev*
markings need to be removed.
This change removes the use of __devinit, __devexit_p, __devinitdata,
__devinitconst, and __devexit from these drivers.
Based on patches originally written by Bill Pemberton, but redone by me
in order to handle some of the coding style issues better, by hand.
Cc: Bill Pemberton <wfp5p@virginia.edu>
Cc: Adam Radford <linuxraid@lsi.com>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Simple conversions to drop flush_scheduled_work() usages in
drivers/scsi. More involved ones will be done in separate patches.
* NCR5380, megaraid_sas: cancel_delayed_work() +
flush_scheduled_work() -> cancel_delayed_work_sync().
* mpt2sas_scsih: drop unnecessary flush_scheduled_work().
* arcmsr_hba, ipr, pmcraid: flush the used work explicitly instead of
using flush_scheduled_work().
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Move the mid-layer's ->queuecommand() invocation from being locked
with the host lock to being unlocked to facilitate speeding up the
critical path for drivers who don't need this lock taken anyway.
The patch below presents a simple SCSI host lock push-down as an
equivalent transformation. No locking or other behavior should change
with this patch. All existing bugs and locking orders are preserved.
Additionally, add one parameter to queuecommand,
struct Scsi_Host *
and remove one parameter from queuecommand,
void (*done)(struct scsi_cmnd *)
Scsi_Host* is a convenient pointer that most host drivers need anyway,
and 'done' is redundant to struct scsi_cmnd->scsi_done.
Minimal code disturbance was attempted with this change. Most drivers
needed only two one-line modifications for their host lock push-down.
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Acked-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Besides keeping the line short, the second setting of the MR_DMA_MODE bit
was removed.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Many release() methods that are not __exit or __devexit call this
__devexit function, so remove its "__devexit" attribute.
scsi/g_NCR5380.c:
WARNING: vmlinux.o(.text+0xadaf8c): Section mismatch: reference to .exit.text:NCR5380_exit (between 'generic_NCR5380_release_resources' and 'generic_NCR5380_biosparam')
WARNING: vmlinux.o(.text+0xadd18c): Section mismatch: reference to .exit.text:NCR5380_exit (between 'generic_NCR5380_release_resources' and 'generic_NCR5380_biosparam')
scsi/pas16.c, seagate.c:
WARNING: vmlinux.o(.text+0xb29e91): Section mismatch: reference to .exit.text:NCR5380_exit (between 'pas16_release' and 'seagate_st0x_info')
t128.c:
WARNING: vmlinux.o(.text+0xb2a774): Section mismatch: reference to .exit.text:NCR5380_exit (between 't128_release' and 't128_biosparam')
dtc.c, sym2/sym_fw.c:
WARNING: vmlinux.o(.text+0xb2f215): Section mismatch: reference to .exit.text:NCR5380_exit (between 'dtc_release' and 'sym_fw1_patch')
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
* remove unnecessary cast
* remove unnecessary use of 'irq' function arg
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
- This patch depends on:
NCR5380: Use scsi_eh API for REQUEST_SENSE invocation
- convert to accessors and !use_sg cleanup
- FIXME: Not sg-chain ready look for ++cmd->SCp.buffer
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: James <James.Bottomley@HansenPartnership.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
- Use new scsi_eh_prep/restor_cmnd() for synchronous
REQUEST_SENSE invocation.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
All these drivers meant to call ->scsi_done() but got confused.
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
* master.kernel.org:/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6: (166 commits)
[SCSI] ibmvscsi: convert to use the data buffer accessors
[SCSI] dc395x: convert to use the data buffer accessors
[SCSI] ncr53c8xx: convert to use the data buffer accessors
[SCSI] sym53c8xx: convert to use the data buffer accessors
[SCSI] ppa: coding police and printk levels
[SCSI] aic7xxx_old: remove redundant GFP_ATOMIC from kmalloc
[SCSI] i2o: remove redundant GFP_ATOMIC from kmalloc from device.c
[SCSI] remove the dead CYBERSTORMIII_SCSI option
[SCSI] don't build scsi_dma_{map,unmap} for !HAS_DMA
[SCSI] Clean up scsi_add_lun a bit
[SCSI] 53c700: Remove printk, which triggers because of low scsi clock on SNI RMs
[SCSI] sni_53c710: Cleanup
[SCSI] qla4xxx: Fix underrun/overrun conditions
[SCSI] megaraid_mbox: use mutex instead of semaphore
[SCSI] aacraid: add 51245, 51645 and 52245 adapters to documentation.
[SCSI] qla2xxx: update version to 8.02.00-k1.
[SCSI] qla2xxx: add support for NPIV
[SCSI] stex: use resid for xfer len information
[SCSI] Add Brownie 1200U3P to blacklist
[SCSI] scsi.c: convert to use the data buffer accessors
...
Fix various bits of obviously-busted code which we're not happening to
compile, due to ifdefs.
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Jan Kara <jack@ucw.cz>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
squish these:
drivers/scsi/NCR5380.c:360: warning: 'phases' defined but not used
drivers/scsi/NCR5380.c:360: warning: 'phases' defined but not used
drivers/scsi/NCR5380.c:633: warning: 'NCR5380_print_options' defined but not used
drivers/scsi/NCR5380.c:708: warning: 'NCR5380_proc_info' defined but not used
drivers/scsi/NCR5380.c:360: warning: 'phases' defined but not used
drivers/scsi/NCR5380.c:579: warning: 'NCR5380_probe_irq' defined but not used
drivers/scsi/NCR5380.c:360: warning: 'phases' defined but not used
drivers/scsi/NCR5380.c:708: warning: 'notyet_generic_proc_info' defined but not used
drivers/scsi/NCR5380.c:708: warning: 'notyet_generic_proc_info' defined but not used
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Replaced yield() with cond_resched()
Signed-off-by: Amol Lad <amol@verismonetworks.com>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.
The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around. On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).
Where appropriate, an arch may override the generic storage facility and do
something different with the variable. On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.
Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions. Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller. A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.
I've build this code with allyesconfig for x86_64 and i386. I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.
This will affect all archs. Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:
struct pt_regs *old_regs = set_irq_regs(regs);
And put the old one back at the end:
set_irq_regs(old_regs);
Don't pass regs through to generic_handle_irq() or __do_IRQ().
In timer_interrupt(), this sort of change will be necessary:
- update_process_times(user_mode(regs));
- profile_tick(CPU_PROFILING, regs);
+ update_process_times(user_mode(get_irq_regs()));
+ profile_tick(CPU_PROFILING);
I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().
Some notes on the interrupt handling in the drivers:
(*) input_dev() is now gone entirely. The regs pointer is no longer stored in
the input_dev struct.
(*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does
something different depending on whether it's been supplied with a regs
pointer or not.
(*) Various IRQ handler function pointers have been moved to type
irq_handler_t.
Signed-Off-By: David Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
Various scsi drivers use scsi_cmnd.buffer and scsi_cmnd.bufflen in their
queuecommand functions. Those fields are internal storage for the
midlayer only and are used to restore the original payload after
request_buffer and request_bufflen have been overwritten for EH. Using
the buffer and bufflen fields means they do very broken things in error
handling.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Rename scsi_print_msg to spi_print_msg and move its prototype from
scsi_dbg.h to scsi_transport_spi.h
Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Use schedule_timeout_uninterruptible() instead of
set_current_state()/schedule_timeout() to reduce kernel size.
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Wrap a highly common idiom. Makes the code easier to read, helps pave
the way for sdev->{id,channel} removal, and adds a token that can easily
by grepped-for in the future.
There are a couple sdev_id() and scmd_printk() updates thrown in as well.
Rejections fixed up and
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Fix 12 undefined preprocessor identifier warnings (4 each in 3 driver builds):
drivers/scsi/NCR5380.c:2744:16: warning: undefined preprocessor identifier 'NDEBUG_ABORT'
drivers/scsi/NCR5380.c:2744:16: warning: "NDEBUG_ABORT" is not defined
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
NDEBUG and NDEBUG_ABORT are almost always used as integers in NCR5380; added
define to 0 if they are not defined, switched lone ifdef NDEBUG into if.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Drivers need not implement a hook that returns FAILED, and does nothing
else, since the SCSI midlayer code will do that for us.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
We have the scsi_print_* functions in the proper namespace for a long
time now and there weren't a lot users left.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Finn Thain