prereset doesn't bring link online if hardreset is about to happen and
nv_hardreset() may skip if conditions are not right so softreset may
be entered with non-working link status if the system firmware didn't
bring it up before entering OS code which can happen during resume.
This patch makes nv_hardreset() to bring up the link if it's skipping
reset.

This bug was reported by frodone@gmail.com in the following bug entry.

  http://bugzilla.kernel.org/show_bug.cgi?id=14329Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: frodone@gmail.com
Cc: stable@kernel.org
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

At least the nVidia MCP55 controller quite happily supports MSI.
This adds an option to use it. It is disabled by default.
As per feedback by Robert Hancock, it will honour the user
request as the kernel will not enable MSI where the controller
or the specific system configuration do not support it.
Signed-off-by: NTony Vroon <tony@linx.net>
Cc: Robert Hancock <hancockrwd@gmail.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

When I thought it was finally defeated, it came back with vengeance.
The failure cases are ever more convoluted.  Now there is a single
combination which fails boot probing - MCP5x + Intel SSD and there are
two hotplug failure reports on different flavors where softreset fails
to bring up the device.

Through the many bug reports after the switch to hardreset, the
following patterns emerged.

- Softreset during boot always works.

- Hardreset during boot sometimes fails to bring up the link on
  certain comibnations and device signature acquisition is unreliable.

- Hardreset is often necessary after hotplug.

It looks like the old behavior of preferring softreset was somehow
pretty close to the working reset protocol although it could have lost
a device during phy error handling by issuing hardreset.

This patch implements nv_hardreset() which kicks in only for post-boot
(!LOADING) device probing resets.  This should be able to work around
all known problem cases.  This isn't perfect but given the various
hardreset quirks on these controllers, I think this is as good as it
can get.

Tested on mcp5x (swncq), nf3 and ck804 for all both boot, warm and
hot probing cases.

Kudos to all the bug reporters and their painful hours with these damn
controllers.  ;-)
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Robert Hancock <hancockr@shaw.ca>
Reported-by: NDavid Lang <david@lang.hm>
Reported-by: NSamo Vodopivec <lament.email.si@gmail.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

On a timeout call a device specific handler early in the recovery so that
we can complete and process successful commands which timed out due to IRQ
loss or the like rather more elegantly.

[Revised to exclude the timeout handling on a few devices that inherit from
 SFF but are not SFF enough to use the default timeout handler]
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

No functional changes in this patch.
Signed-off-by: NErik Inge Bolsø <knan-lkml@anduin.net>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Update MODULE_PARM_DESC for ADMA to reflect the fact that the
option is disabled by default.
Signed-off-by: NBrandon Ehle <azverkan@yahoo.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Kernel bz#12176 reports that nf2 hardreset simply doesn't work.  Give
up.  Argh...
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Robert Hancock <hancockr@shaw.ca>
Reported-by: NSaro <saro_v@hotmail.it>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

While playing with nvraid, I found out that rmmoding and insmoding
often trigger hardreset failure on the first port (the second one was
always okay).  Seriously, how diverse can you get with hardreset
behaviors?  Anyways, make ck804 use noclassify variant too.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

MCP5x family of controllers seem to share much more with nf2's as far
as reset protocol is concerned.  It requires heardreset to get the PHY
going and classfication code report after hardreset is unreliable.
Create a new board type MCP5x and use noclassify hardreset.  SWNCQ is
modified to inherit from this new type.

This fixes hotplug regression reported in kernel bz#12351.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

nv_nf2_hardreset() will be used by other flavors too.  Rename it to
nv_noclassify_hardreset().
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

All three flavors of sata_nv's are different in how their hardreset
behaves.

* generic: Hardreset is not reliable.  Link often doesn't come online
  after hardreset.

* nf2/3: A little bit better - link comes online with longer debounce
  timing.  However, nf2/3 can't reliable wait for the first D2H
  Register FIS, so it can't wait for device readiness or classify the
  device after hardreset.  Follow-up SRST required.

* ck804: Hardreset finally works.

The core layer change to prefer hardreset and follow up changes
exposed the above issues and caused various detection regressions for
all three flavors.  This patch, hopefully, fixes all the known issues
and should make sata_nv error handling more reliable.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Logically, SCR access ops should take @link; however, there was no
compelling reason to convert all SCR access ops when adding @link
abstraction as there's one-to-one mapping between a port and a non-PMP
link.  However, that assumption won't hold anymore with the scheduled
addition of slave link.

Make SCR access ops per-link.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Commit 2fd673ec which tried to remove
hardreset for generic accidentally removed it for all flavors as all
others were inheriting from nv_generic_ops.  This patch reinstates
nv_hardreset() and puts it into nv_common_ops which all flavors
inherit from.  nv_generic_ops now inherits from nv_common_ops and
overrides .hardreset to ATA_OP_NULL.

While at it, explain why nv_hardreset and ATA_OP_NULL override are
necessary.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

of them being unifying probing, hotplug and EH reset paths uniform.
Previously, broken hardreset could go unnoticed as it wasn't used
during probing but when something goes wrong or after hotplug the
problem will surface and bite hard.

OSDL bug 11195 reports that sata_nv generic flavor falls into this
category.  Hardreset itself succeeds but PHY stays offline after
hardreset.  I tried longer debounce timing but the result was the
same.

  http://bugzilla.kernel.org/show_bug.cgi?id=11195

So, it seems we'll have to drop hardreset from the generic flavor.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Peer Chen <pchen@nvidia.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

sata_nv hardreset can't classify but was left out while unifying
follow-up SRST request mechanism[1].  This caused detection failures
on those controllers.  Fix it.

Reported and bisected by Roland Dreier, Petr Vandrovec and Marc
Dionne.  Thanks guys.

[1] 305d2a1aSigned-off-by: NTejun Heo <htejun@gmail.com>
Cc: Roland Dreier <rdreier@cisco.com>
Cc: Petr Vandrovec <vandrove@vc.cvut.cz>
Cc: Marc Dionne <marc.c.dionne@gmail.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Add sff_ prefix to SFF specific port ops.

This rename is in preparation of separating SFF support out of libata
core layer.  This patch strictly renames ops and doesn't introduce any
behavior difference.
Signed-off-by: NTejun Heo <htejun@gmail.com>

SFF functions have confusing names.  Some have sff prefix, some have
bmdma, some std, some pci and some none.  Unify the naming by...

* SFF functions which are common to both BMDMA and non-BMDMA are
  prefixed with ata_sff_.

* SFF functions which are specific to BMDMA are prefixed with
  ata_bmdma_.

* SFF functions which are specific to PCI but apply to both BMDMA and
  non-BMDMA are prefixed with ata_pci_sff_.

* SFF functions which are specific to PCI and BMDMA are prefixed with
  ata_pci_bmdma_.

* Drop generic prefixes from LLD specific routines.  For example,
  bfin_std_dev_select -> bfin_dev_select.

The following renames are noteworthy.

  ata_qc_issue_prot() -> ata_sff_qc_issue()
  ata_pci_default_filter() -> ata_bmdma_mode_filter()
  ata_dev_try_classify() -> ata_sff_dev_classify()

This rename is in preparation of separating SFF support out of libata
core layer.  This patch strictly renames functions and doesn't
introduce any behavior difference.
Signed-off-by: NTejun Heo <htejun@gmail.com>

Continues to have open issues, and engineering support is extremely difficult
to come by, according to fellow NVIDIA engineers.
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Signed-off-by: NZoltan Boszormenyi <zboszor@dunaweb.hu>
Cc: Robert Hancock <hancockr@shaw.ca>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Currently reset methods are not specified directly in the
ata_port_operations table.  If a LLD wants to use custom reset
methods, it should construct and use a error_handler which uses those
reset methods.  It's done this way for two reasons.

First, the ops table already contained too many methods and adding
four more of them would noticeably increase the amount of necessary
boilerplate code all over low level drivers.

Second, as ->error_handler uses those reset methods, it can get
confusing.  ie. By overriding ->error_handler, those reset ops can be
made useless making layering a bit hazy.

Now that ops table uses inheritance, the first problem doesn't exist
anymore.  The second isn't completely solved but is relieved by
providing default values - most drivers can just override what it has
implemented and don't have to concern itself about higher level
callbacks.  In fact, there currently is no driver which actually
modifies error handling behavior.  Drivers which override
->error_handler just wraps the standard error handler only to prepare
the controller for EH.  I don't think making ops layering strict has
any noticeable benefit.

This patch makes ->prereset, ->softreset, ->hardreset, ->postreset and
their PMP counterparts propoer ops.  Default ops are provided in the
base ops tables and drivers are converted to override individual reset
methods instead of creating custom error_handler.

* ata_std_error_handler() doesn't use sata_std_hardreset() if SCRs
  aren't accessible.  sata_promise doesn't need to use separate
  error_handlers for PATA and SATA anymore.

* softreset is broken for sata_inic162x and sata_sx4.  As libata now
  always prefers hardreset, this doesn't really matter but the ops are
  forced to NULL using ATA_OP_NULL for documentation purpose.

* pata_hpt374 needs to use different prereset for the first and second
  PCI functions.  This used to be done by branching from
  hpt374_error_handler().  The proper way to do this is to use
  separate ops and port_info tables for each function.  Converted.
Signed-off-by: NTejun Heo <htejun@gmail.com>

libata core layer doesn't care about sht or ->irq_handler.  Those are
only of interest to the LLD during initialization.  This is confusing
and has caused several drivers to have duplicate unused initializers
for these fields.

Currently only sata_nv uses these fields.  Make sata_nv use
->private_data, which is supposed to carry LLD-specific information,
instead and kill ->sht and ->irq_handler.  nv_pi_priv structure is
defined and struct literals are used to initialize private_data.
Notational overhead is negligible.
Signed-off-by: NTejun Heo <htejun@gmail.com>

libata lets low level drivers build ata_port_operations table and
register it with libata core layer.  This allows low level drivers
high level of flexibility but also burdens them with lots of
boilerplate entries.

This becomes worse for drivers which support related similar
controllers which differ slightly.  They share most of the operations
except for a few.  However, the driver still needs to list all
operations for each variant.  This results in large number of
duplicate entries, which is not only inefficient but also error-prone
as it becomes very difficult to tell what the actual differences are.

This duplicate boilerplates all over the low level drivers also make
updating the core layer exteremely difficult and error-prone.  When
compounded with multi-branched development model, it ends up
accumulating inconsistencies over time.  Some of those inconsistencies
cause immediate problems and fixed.  Others just remain there dormant
making maintenance increasingly difficult.

To rectify the problem, this patch implements ata_port_operations
inheritance.  To allow LLDs to easily re-use their own ops tables
overriding only specific methods, this patch implements poor man's
class inheritance.  An ops table has ->inherits field which can be set
to any ops table as long as it doesn't create a loop.  When the host
is started, the inheritance chain is followed and any operation which
isn't specified is taken from the nearest ancestor which has it
specified.  This operation is called finalization and done only once
per an ops table and the LLD doesn't have to do anything special about
it other than making the ops table non-const such that libata can
update it.

libata provides four base ops tables lower drivers can inherit from -
base, sata, pmp, sff and bmdma.  To avoid overriding these ops
accidentaly, these ops are declared const and LLDs should always
inherit these instead of using them directly.

After finalization, all the ops table are identical before and after
the patch except for setting .irq_handler to ata_interrupt in drivers
which didn't use to.  The .irq_handler doesn't have any actual effect
and the field will soon be removed by later patch.

* sata_sx4 is still using old style EH and currently doesn't take
  advantage of ops inheritance.
Signed-off-by: NTejun Heo <htejun@gmail.com>

libata lets low level drivers build scsi_host_template and register it
to the SCSI layer.  This allows low level drivers high level of
flexibility but also burdens them with lots of boilerplate entries.

This patch implements SHT initializers which can be used to initialize
all the boilerplate entries in a sht.  Three variants of them are
implemented - BASE, BMDMA and NCQ - for different types of drivers.
Note that entries can be overriden by putting individual initializers
after the helper macro.

All sht tables are identical before and after this patch.
Signed-off-by: NTejun Heo <htejun@gmail.com>

Over the time, port info, ops and sht structures developed quite a bit
of inconsistencies.  This patch updates drivers.

* Enable/disable_pm callbacks added to all ahci ops tables.

* Every driver for SFF controllers now uses ata_sff_port_start()
  instead of ata_port_start() unless the driver has custom
  implementation.

* Every driver for SFF controllers now uses ata_pci_default_filter()
  unless the driver has custom implementation.

* Removed an odd port_info->sht initialization from ata_piix.c.
  Likely a merge byproduct.

* A port which has ATA_FLAG_SATA set doesn't need to set cable_detect
  to ata_cable_sata().  Remove it from via and mv port ops.

* Some drivers had unnecessary .max_sectors initialization which is
  ignored and was missing .slave_destroy callback.  Fixed.

* Removed unnecessary sht initializations port_info's.

* Removed onsolete scsi device suspend/resume callbacks from
  pata_bf54x.

* No reason to set ata_pci_default_filter() and bmdma functions for
  PIO-only drivers.  Remove those callbacks and replace
  ata_bmdma_irq_clear with ata_noop_irq_clear.

* pata_platform sets port_start to ata_dummy_ret0.  port_start can
  just be set to NULL.

* sata_fsl supports NCQ but was missing qc_defer.  Fixed.

* pata_rb600_cf implements dummy port_start.  Removed.
Signed-off-by: NTejun Heo <htejun@gmail.com>

Now that hardreset is the preferred method of resetting, there's no
need for ATA_LFLAG_HRST_TO_RESUME flag.  Kill it.
Signed-off-by: NTejun Heo <htejun@gmail.com>

When both soft and hard resets are available, libata preferred
softreset till now.  The logic behind it was to be softer to devices;
however, this doesn't really help much.  Rationales for the change:

* BIOS may freeze lock certain things during boot and softreset can't
  unlock those.  This by itself is okay but during operation PHY event
  or other error conditions can trigger hardreset and the device may
  end up with different configuration.

  For example, after a hardreset, previously unlockable HPA can be
  unlocked resulting in different device size and thus revalidation
  failure.  Similar condition can occur during or after resume.

* Certain ATAPI devices require hardreset to recover after certain
  error conditions.  On PATA, this is done by issuing the DEVICE RESET
  command.  On SATA, COMRESET has equivalent effect.  The problem is
  that DEVICE RESET needs its own execution protocol.

  For SFF controllers with bare TF access, it can be easily
  implemented but more advanced controllers (e.g. ahci and sata_sil24)
  require specialized implementations.  Simply using hardreset solves
  the problem nicely.

* COMRESET initialization sequence is the norm in SATA land and many
  SATA devices don't work properly if only SRST is used.  For example,
  some PMPs behave this way and libata works around by always issuing
  hardreset if the host supports PMP.

  Like the above example, libata has developed a number of mechanisms
  aiming to promote softreset to hardreset if softreset is not going
  to work.  This approach is time consuming and error prone.

  Also, note that, dependingon how you read the specs, it could be
  argued that PMP fan-out ports require COMRESET to start operation.
  In fact, all the PMPs on the market except one don't work properly
  if COMRESET is not issued to fan-out ports after PMP reset.

* COMRESET is an integral part of SATA connection and any working
  device should be able to handle COMRESET properly.  After all, it's
  the way to signal hardreset during reboot.  This is the most used
  and recommended (at least by the ahci spec) method of resetting
  devices.

So, this patch makes libata prefer hardreset over softreset by making
the following changes.

* Rename ATA_EH_RESET_MASK to ATA_EH_RESET and use it whereever
  ATA_EH_{SOFT|HARD}RESET used to be used.  ATA_EH_{SOFT|HARD}RESET is
  now only used to tell prereset whether soft or hard reset will be
  issued.

* Strip out now unneeded promote-to-hardreset logics from
  ata_eh_reset(), ata_std_prereset(), sata_pmp_std_prereset() and
  other places.
Signed-off-by: NTejun Heo <htejun@gmail.com>

This fixes some problems with ATAPI devices on nForce4 controllers in ADMA mode
on systems with memory located above 4GB. We need to delay setting the 64-bit
DMA mask until the PRD table and padding buffer are allocated so that they don't
get allocated above 4GB and break legacy mode (which is needed for ATAPI
devices). Also, if either port is in ATAPI mode we need to set the DMA mask
for the PCI device to 32-bit to ensure that the IOMMU code properly bounces
requests above 4GB, as it appears setting the bounce limit does not guarantee
that we will not try to map requests above this point.

Reported to fix https://bugzilla.redhat.com/show_bug.cgi?id=351451Signed-off-by: NRobert Hancock <hancockr@shaw.ca>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

This patch is based on an original patch from Kuan Luo of NVIDIA,
posted under subject "fixed a bug of adma in rhel4u5 with HDS7250SASUN500G".
His description follows. I've reworked it a bit to avoid some unnecessary
repeated checks but it should be functionally identical.

"The patch is to solve the error message "ata1: CPB flags CMD err,
flags=0x11" when testing HDS7250SASUN500G in rhel4u5.
I tested this hd in 2.6.24-rc7 which needed to remove the mask in
blacklist to run the ncq and the same error also showed up.

I traced the  bug and found that the interrupt finished a command (for
example, tag=0) when the driver got that adma status is
NV_ADMA_STAT_DONE  and  cpb->resp_flags is NV_CPB_RESP_DONE.
However, For this hd, the drive maybe didn't clear bit 0 at this moment.
It meaned the hardware  had not completely finished the command.
If at the same time  the driver freed the command(tag 0) and sended
another command (tag 0), the error happened.

The notifier register is 32-bit register containing notifier value.
Value is bit vector containing one bit per tag number (0-31) in
corresponding bit positions (bit 0 is for tag 0, etc). When bit is set
then ADMA indicates that command with corresponding tag number completed
execution.

So i added the check notifier code. Sometimes i saw that the notifier
reg set some bits  , but the adma status set NV_ADMA_STAT_CMD_COMPLETE
,not NV_ADMA_STAT_DONE. So i added the NV_ADMA_STAT_CMD_COMPLETE check
code."
Signed-off-by: NRobert Hancock <hancockr@shaw.ca>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

libata used private sg iterator to handle padding sg.  Now that sg can
be chained, padding can be handled using standard sg ops.  Convert to
chained sg.

* s/qc->__sg/qc->sg/

* s/qc->pad_sgent/qc->extra_sg[]/.  Because chaining consumes one sg
  entry.  There need to be two extra sg entries.  The renaming is also
  for future addition of other extra sg entries.

* Padding setup is moved into ata_sg_setup_extra() which is organized
  in a way that future addition of other extra sg entries is easy.

* qc->orig_n_elem is unused and removed.

* qc->n_elem now contains the number of sg entries that LLDs should
  map.  qc->mapped_n_elem is added to carry the original number of
  mapped sgs for unmapping.

* The last sg of the original sg list is used to chain to extra sg
  list.  The original last sg is pointed to by qc->last_sg and the
  content is stored in qc->saved_last_sg.  It's restored during
  ata_sg_clean().

* All sg walking code has been updated.  Unnecessary assertions and
  checks for conditions the core layer already guarantees are removed.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

We need to run any DMA command with result taskfile requested in ADMA mode
when the port is in ADMA mode, otherwise it may try to use the legacy DMA engine
in ADMA mode which is not allowed. Enforce this with BUG_ON() since data
corruption could potentially result if this happened. Also, fail any attempt to
try and issue NCQ commands with result taskfile requested, since the hardware
doesn't allow this.
Signed-off-by: NRobert Hancock <hancockr@shaw.ca>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NFernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Adapted from patches by Kuan Lou @ NVIDIA and Bartlomiej Zolnierkiewicz.
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

The mcp61 has bug with ncq.
Signed-off-by: NKuan Luo <kluo@nvidia.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Tackle the relatively sane complaints of checkpatch --file.

The vast majority is indentation and whitespace changes, the rest are

* #include fixes
* printk KERN_xxx prefix addition
* BSS/initializer cleanups
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Add the Software NCQ support to sata_nv.c for MCP51/MCP55/MCP61 SATA
controller.  NCQ function is disable by default, you can enable it
with 'swncq=1'.  NCQ will be turned off if the drive is Maxtor on
MCP51 or MCP55 rev 0xa2 platform.

[akpm@linux-foundation.org: build fix]
Signed-off-by: NKuan Luo <kluo@nvidia.com>
Signed-off-by: NPeer Chen <pchen@nvidia.com>
Cc: Zoltan Boszormenyi <zboszor@dunaweb.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Controllers which support PMP have various restrictions on which
combinations of commands are allowed to what number of devices
concurrently.  This patch implements ops->qc_defer() which determines
whether a qc can be issued at the moment or should be deferred.

If the function returns ATA_DEFER_LINK, the qc will be deferred until
a qc completes on the link.  If ATA_DEFER_PORT, until a qc completes
on any link.  The defer conditions are advisory and in general
ATA_DEFER_LINK can be considered as lower priority deferring than
ATA_DEFER_PORT.

ops->qc_defer() replaces fixed ata_scmd_need_defer().  For standard
NCQ/non-NCQ exclusion, ata_std_qc_defer() is implemented.  ahci and
sata_sil24 are converted to use ata_std_qc_defer().

ops->qc_defer() is heavier than the original mechanism because full qc
is prepped before determining to defer it, but various information is
needed to determine defer conditinos and fully translating a qc is the
only way to supply such information in generic manner.

IMHO, this shouldn't cause any noticeable performance issues as

* for most cases deferring occurs rarely (except for NCQ-aware
  cmd-switching PMP)
* translation itself isn't that expensive
* once deferred the command won't be repeated until another command
  completes which usually is a very long time cpu-wise.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

It was always set to ata_port_disable().  Removed the hook, and replaced
the very few ap->ops->port_disable() callsites with direct calls to
ata_port_disable().
Signed-off-by: NJeff Garzik <jeff@garzik.org>

* ->irq_ack() is redundant to what the irq handler already
  performs... chk-status + irq-clear.  Furthermore, it is only
  called in one place, when screaming-irq-debugging is enabled,
  so we don't want to bother with a hook just for that.

* ata_dummy_irq_on() is only ever used in drivers that have
  no callpath reaching ->irq_on().  Remove .irq_on hook from
  those drivers, and the now-unused ata_dummy_irq_on()
Signed-off-by: NJeff Garzik <jeff@garzik.org>