only for now, but wouldn't be too difficult to add support for FDT.
Reviewed by: hselasky
Obtained from: ABT Systems Ltd
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D7352
Just as most of other drivers do. And move sysinit function close
to its SYSINIT.
MFC after: 1 week
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D7347
New design allows hardware resources to be split between several consumers.
For example, one BAR can be dedicated for remote memory access, while other
resources can be used for packet transport for virtual Ethernet interface.
And even without resource split, this code allows to specify which consumer
driver should attach the hardware.
From some points this makes the code even closer to Linux one, even though
Linux does not provide the described flexibility.
* Makes the TX DMA stopping more similar to Linux code, and potentially
a bit faster. Also, output an error message when TX DMA idling fails.
Taken-From: Linux iwlwifi
Tested:
* AC3165, STA mode
Approved by: adrian (mentor)
Obtained from: DragonFlyBSD git 2ee486ddff973ac552ff787c17e8d83e8ae0f24c
Differential Revision: https://reviews.freebsd.org/D7325
When building a Tx Command for management frames, we are lacking
a check for action frames, for which we should set a different
pm_timeout. This cause the fw to stay awake for 100TU after each
such frame is transmitted, resulting an excessive power consumption.
Taken-From: Linux iwlwifi (git b084a35663c3f1f7)
Approved by: adrian (mentor)
Obtained from: Linux git b084a35663c3f1f7de1c45c4ae3006864c940fe7
Obtained from: DragonFlyBSD git ba00f0e3ae873d6f0d5743e22c3ebc49c44dfdac
Differential Revision: https://reviews.freebsd.org/D7324
The PROT_REQUIRE flag in should be set for data frames above a certain
length, but we were setting it for !data frames above a certain length,
which makes no sense at all.
Taken-From: OpenBSD, Linux iwlwifi
Approved by: adrian (mentor)
Obtained from: DragonFlyBSD git 8cc03924a36c572c2908e659e624f44636dc2b33
Differential Revision: https://reviews.freebsd.org/D7323
AIO write requests for a TOE socket on a Chelsio T4+ adapter can now
DMA directly from the user-supplied buffer. This is implemented by
wiring the pages backing the user-supplied buffer and queueing special
mbufs backed by raw VM pages to the socket buffer. The TOE code
recognizes these special mbufs and builds a sglist from the VM page
array associated with the mbuf when queueing a work request to the TOE.
Because these mbufs do not have an associated virtual address, m_data
is not valid. Thus, the AIO handler does not invoke sosend() directly
for these mbufs but instead inlines portions of sosend_generic() and
tcp_usr_send().
An aiotx_buffer structure is used to describe the user buffer (e.g.
it holds the array of VM pages and a reference to the AIO job). The
special mbufs reference this structure via m_ext. Note that a single
job might be split across multiple mbufs (e.g. if it is larger than
the socket buffer size). The 'ext_arg2' member of each mbuf gives an
offset relative to the backing aiotx_buffer. The AIO job associated
with an aiotx_buffer structure is completed when the last reference to
the structure is released.
Zero-copy aio_write()'s for connections associated with a given
adapter can be enabled/disabled at runtime via the
'dev.t[45]nex.N.toe.tx_zcopy' sysctl.
MFC after: 1 month
Relnotes: yes
Sponsored by: Chelsio Communications
So that they can use suitable MP synchronization mechanism.
While I'm here change the bufring init/read/write function names.
MFC after: 1 week
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D7313
returning EAGAIN if they aren't available when the user tries to program
a filter. Do this after validating the filter so that the driver
doesn't bring up the queues if it doesn't have to.
The hardware delivers ns16550-compatible status bits, which is what the
usb_serial code expects, so no need for translation, no need for a local
variable to hold a temporary lsr result.
Note that keyboards are stored in an array and are not freed (just
"unregistered" by clearing some fields) so a race would be limited to
obtaining stale information about an unregistered keyboard.
Reported by: CTurt
MFC after: 3 days
It only contains bufring related bits for a while.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7281
Calling it earlier increases the window when MSIX info may change.
This change does not solve the problem completely, but seems logical.
Complete solution should probably include link reset in case of MSIX
remap to trigger new negotiation, but we have no way to get notified
about that now.
Split implementation of nvram2env to generic (MI) & MIPS-based code:
- removed includes like "*siba*", because they are unused
- added nvram2env_mips.c file with MIPS-specific code, code moved from nvram2env.c
- added header file to shared defines/structures/function prototypes between MI and MIPS code
Also this fix allows to implement own nvram2env drivers.
Reviewed by: ray, adrian (mentor)
Approved by: adrian (mentor)
Differential Revision: https://reviews.freebsd.org/D6513
vesa_init_done isn't a reliable guard for the mutex init. If
vesa_configure() doesn't find valid VESA info it will not set
vesa_init_done, but the lock will remain initialized. Revert r303076
and use MTX_SYSINIT to deterministically init the lock.
Reviewed by: royger
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D7290
Chelsio NICs are a bit unique compared to some other NICs in that they
expose different functionality on different physical functions. In
particular, PF4 is used to manage the NIC interfaces ('t4nex' and 't5nex').
However, PF4 is not able to create VF devices. Instead, VFs are only
supported by physical functions 0 through 3. This commit adds 't4iov'
and 't5iov' drivers that attach to PF0-3.
One extra wrinkle is that the iov devices cannot enable SR-IOV until the
firwmare has been initialized by the main PF4 driver. To handle this
case, a new t4_if kobj interface has been added to permit cross-calls
between the PF drivers. The PF4 driver notifies sibling drivers when it
is fully attached. It also requests sibling drivers to detach before it
detaches. Sibling drivers query the PF4 driver during their attach
routine to see if it is attached. If not, the sibling drivers defer
their attach actions until the PF4 driver informs them it is attached.
VF devices are associated with a single port on the NIC. VF devices
created from PF0 are associated with the first port on the NIC, VFs
from PF1 are associated with the second port, etc. VF devices can
only be created from a PF device that has an associated port. Thus,
on a 2-port card, VFs are only supported on PF0 and PF1.
Reviewed by: np (earlier versions)
MFC after: 1 month
Sponsored by: Chelsio Communications
If a driver sends an malformed or disallowed work request, the firmware
responds with a work request error. Previously the driver treated this is
as an unexpected message and panicked. Now it decodes the error message
to aid in debugging.
Reviewed by: np (older version)
MFC after: 1 month
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D6950
Binary state node is added, so that userland programs do not have
to parse human readable state string.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7268
warnings for some kernel events, mostly intended for the use of
obsoleted or otherwise undersired interfaces.
This is an abstracted and race-expelled code from compat pty driver.
Requested and reviewed by: jhb
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D7270
* Add acpi_if.h to the SRC list in the uart module
* Only include new acpi headers when they are needed
Obtained from: ABT Systems Ltd
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
the uart class to use in a similar way as the fdt driver.
Obtained from: ABT Systems Ltd
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D7248
This avoids unnecessary access to the vmbus_softc struct on sending path.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7257
Clear unused (undocumented) CAM bytes while setting a key;
without that, hardware does weird things when A-MSDU bit in QoS header
is set.
Tested with RTL8188CUS (AP) -> RTL8188EU (STA) (A-MSDU transmit).
Reported by: many
Obtained from: https://github.com/s3erios/urtwm
MFC after: 5 days
and ACPI. As such pull out what will be the common parts of the FDT cpu
detection to a new function that can be shared between them.
Reviewed by: manu
Obtained from: ABT Systems Ltd
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D7262
Fix the following panic seen when migrating a FreeBSD guest on Xen:
panic: mtx_lock() of destroyed mutex @ /usr/src/sys/dev/fb/vesa.c:541
cpuid = 0
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe001d2fa4f0
vpanic() at vpanic+0x182/frame 0xfffffe001d2fa570
kassert_panic() at kassert_panic+0x126/frame 0xfffffe001d2fa5e0
__mtx_lock_flags() at __mtx_lock_flags+0x15b/frame 0xfffffe001d2fa630
vesa_bios_save_restore() at vesa_bios_save_restore+0x78/frame 0xfffffe001d2fa680
vga_suspend() at vga_suspend+0xa3/frame 0xfffffe001d2fa6b0
isavga_suspend() at isavga_suspend+0x1d/frame 0xfffffe001d2fa6d0
bus_generic_suspend_child() at bus_generic_suspend_child+0x44/frame
[...]
This is caused because vga_sub_configure (which is called if the VGA adapter
is attached after VESA tried to initialize), points to vesa_configure, which
doesn't initialize the VESA mutex. In order to fix it, make sure
vga_sub_configure points to vesa_load, so that all the needed vesa
components are properly initialized.
Sponsored by: Citrix Systems R&D
MFC after: 3 days
PR: 209203
Reviewed by: dumbbell
Differential revision: https://reviews.freebsd.org/D7196
The prepares to kill device private fields in channel struct, which
are not flexible and extensible.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7243
And rename "DEFAULT" constants to the more accurate "MAX."
PR: 210382
Submitted by: Felix <felixphew0 at gmail.com>
Reviewed by: wblock, cem
Tested by: Dave Cottlehuber <dch at skunkwerks.at>
And create cpu to channel map at device attach time for storvsc(4).
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7229
The 11n duration calculation function in net80211 and the HAL round /up/
the duration calculation for short-gi, so we can't use that.
The 11n duration calculation doesn't know about the extra symbol time
needed for STBC, nor the LDPC encoding duration, so we can't use
that.
This (along with other, local hacks) allow the locationing services to
get down to around 200nS (yes, nanoseconds) of variance when speaking
to a "good" AP.
Tested:
* AR9380, STA mode, local locationing frame hacks
In particular for me this fixes checksum problem when if_bridge attached
to the interface requests TXCSUM to be disabled, but effectively ignored.
MFC after: 3 days
Sponsored by: iXsystems, Inc.
- add new rman for prefetchable memory. Is used only if given 'ranges'
property contains prefetchable memory range.
- not all ranges in 'ranges' property are subject for rman's filling.
Tegra for example, have two addition records which are used for
'pci 'register' -> 'assigned-address' -> 'ranges' machinery.
Add sc_ranges_mask for masking not rman related ranges.
- consistently pass unknown (not managed at this level) resources
allocation/release/adjust requests to parent.
MFC after: 3 weeks
This is probably a NOP change since IS register is not activery used for
interrupts below the shared, but it looked odd to clear interrupts we did
not handle.
The pre-11n calculations include SIFS, but the 11n ones don't.
The reason is that (mostly) the 11n hardware is doing the SIFS calculation
for us but the pre-11n hardware isn't. This means that we're over-shooting
the times in the duration field for non-11n frames on 11n hardware, which
is OK, if not a little inefficient.
Now, this is all fine for what the hardware needs for doing duration math
for ACK, RTS/CTS, frame length, etc, but it isn't useful for doing PHY
duration calculations. Ie, given a frame to TX and its timestamp, what
would the end of the actual transmission time be; and similar for an
RX timestamp and figuring out its original length.
So, this adds a new field to the duration routines which requests
SIFS or no SIFS to be included. All the callers currently will call
it requesting SIFS, so this /should/ be a glorious no-op. I'm however
planning some future work around airtime fairness and positioning which
requires these routines to have SIFS be optional.
Notably though, the 11n version doesn't do any SIFS addition at the moment.
I'll go and tweak and verify all of the packet durations before I go and
flip that part on.
Tested:
* AR9330, STA mode
* AR9330, AP mode
* AR9380, STA mode
The channel packet header will be shared w/ PRP (physical region page)
list channel packet and SG (scatter gather) list channel packet.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7155
Mainly for compatibility. While I'm here, rename cpuid related
fields in hv_vmbus_channel.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7141
just with INVARIANTS
rwatson's point was valid in the sense that if the data passed at runtime is
invalid, it should always trip the invariant, not just in the debug case.
This is a deterrent against malicious input, or input caused by hardware
errors.
MFC after: 4 days
X-MFC with: r302577
Requested by: rwatson
Sponsored by: EMC / Isilon Storage Division
It is not safe to iterate the sub-channel list w/o lock on the
close path, while it's even more difficult to hold the lock
and iterate the sub-channel list. We leverage the
vmbua_{get,rel}_subchan() functions to solve this dilemma.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7112
Device detach method may sleep.
While I'm here, rename the function, fix indentation and function
comment.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7110
- Make the vmbus_chan_add more straightforward.
- Partially fix the hv_vmbus_release_unattached_channels().
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7109
In case that VMBUS_CHAN_ISPRIMARY is needed in the early place of
channel setup.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7108
This paves the way for more cleanup/disentangle.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7102
This paves way for the further cleanup/disentangle.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7092
This avoids bunch of unnecessary checks on hot path and simplifies the
channel processing.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7085
This paves way to nuke the hv_device, which is actually an unncessary
indirection.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7033
This paves way to nuke the hv_device, which is actually an unncessary
indirection.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7032
This paves way to nuke the hv_device, which is actually an unncessary
indirection.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7028
This paves way to nuke the hv_device, which is actually an unncessary
indirection.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7027
This makes life easier during the transition period to nuke the hv_device.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7026
This prepares to remove the unnecessary offer message embedding in
hv_vmbus_channel.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7020
This prepares to remove the unnecessary offer message embedding in
hv_vmbus_channel.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7019
This prepares to remove the unnecessary offer message embedding in
hv_vmbus_channel.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7015
This prepares to remove the unnecessary offer message embedding in
hv_vmbus_channel.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7014
For multi-channel devices, once the primary channel is closed,
a set of 'rescind' messages for sub-channels will be delivered
by Hypervisor. Sub-channel MUST be freed according to these
'rescind' messages; directly re-openning sub-channels in the
same fashion as the primary channel's re-opening does NOT work
at all.
After the primary channel is re-opened, requested # of sub-
channels will be delivered though 'channel offer' messages, and
this set of newly offered channels can be opened along side with
the primary channel.
This unbreaks the MTU setting for hn(4), which requires re-
openning all existsing channels upon MTU change.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6978
Instead of global variable, vmbus version is accessed through
a vmbus DEVMETHOD now.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6953
Pin the channel to cpu0 by default. Drivers having special channel-cpu
mapping requirement should call vmbus_channel_cpu_{set,rr}() themselves.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6918
This also fixes memory leakge if sub-connect messages are needed.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6878
The current command response handling discards status and xfer
length unconditionally, so that all of the commands would be
considered successful, even if errors happened. When errors
really happens, this causes all kinds of wiredness, since the
buffer will not be filled on the host side and sense data will
be ignored.
Most of the time, errors do not happen, however, error does
happen for the request sent immediately after the disk resizing.
Discarding the SCSI status (SCSI_STATUS_CHECK_COND) and sense
data (capacity changes) prevents the disk resizing from working
properly.
This commit saves the response status and xfer length properly
for later use.
Submitted by: Dexuan Cui <decui microsoft com>
Noticed by: sephe
MFC after: 3 days
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D7181
NVRAM, ChipCommon, etc).
This extends the existing handling of NVRAM core discovery to support
locating additional devices that may be attached either directly as real
cores, or indirectly via ChipCommon (e.g. bhnd_pmu).
When attached as a SoC root bus (as opposed to a bridged WiFi device),
the platform devices may not be attached until later bus passes,
necessitating delayed discovery/initialization.
Approved by: adrian (mentor)
Differential Revision: https://reviews.freebsd.org/D6962
By definition (enum __drm_capabilities), cases other than CAP_SYS_ADMIN
aren't possible. Add in a KASSERT safety belt and return false in
!INVARIANTS case if an invalid value is passed in, as it would be a
programmer error.
This fixes a -Wreturn-type error with gcc 5.3.0.
Differential Revision: https://reviews.freebsd.org/D7188
MFC after: 1 week
Reported by: devel/amd64-gcc (5.3.0)
Reviewed by: dumbbell
Sponsored by: EMC / Isilon Storage Division
So that we don't need to access the global vmbus softc.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6863
The device probe/attach has been move to a different thread, so the
reasons to create the channel asynchronously are no longer valid.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6862
While I'm here, remove the useless message type from message process
array, which is not used and serves no purposes at all.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6858
And use this new APIs for Initial Contact post message Hypercall.
More post message Hypercalls will be converted.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6830
I don't know what errata is mentioned there, I was unable to find it, but
setting limit before the base simply does not work at all. According to
specification attempt to set limit out of the present window range resets
it to zero, effectively disabling it. And that is what I see in practice.
Fixing this properly disables access for remote side to our memory until
respective xlat is negotiated and set. As I see, Linux does the same.
At that point link is quite likely not established yet, so messing with
scratch registers is premature there. Original commit message mentioned
code diff reduction from Linux, but this line is not present in Linux now.
In some cases, the driver must handle given properties located in
specific OF subnode. Instead of creating duplicate set of function, add
'node' as argument to existing functions, defaulting it to device OF node.
MFC after: 3 weeks
operates on a specific OF node instead of the pass in device's OF node.
Reviewed by: andrew, mmel
Differential Revision: https://reviews.freebsd.org/D6957
The bus_region_* APIs accept the number of data items to be read, while
the code was passing the total number of bytes, resulting in an overflow
of the SPROM parser's buffer.
Approved by: adrian (mentor)
Differential Revision: https://reviews.freebsd.org/D7168
For some reason hack with sending MSI-X interrupts by writing to remote
LAPIC memory works only for 32-bit BARs, that are available only if split
BARs mode is enabled in BIOS. If it is not, complain loudly and fall back
to less efficient workaround.
For compatibility reasons make driver not report any checksum offload by
default, since there is indeed none. But if administrator knows that
interface is used only for local traffic, he can enable fake checksum
offload manually on both sides to save some CPU cycles, since the data
are already protected by CRC32 of PCIe link.
Sponsored by: iXsystems, Inc.
This allows at least first three doorbells to work very close to normal
hardware, properly signaling events to upper layers without spurious or
lost events. Doorbells above the first three may still report spurious
events due to lack of reliable information, but they are rarely used.
It is odd idea to serialize different MSI-X vectors. Use of rmlocks
here allows them to execute in parallel, but still protects ctx.
If upper layers require any additional serialization -- they can
do it by themselves.
This follows NTB subsystem modularization in Linux, tuning it to FreeBSD
native NewBus interfaces. This change allows to support different types
of hardware with different drivers, support multiple NTB instances in a
system, ntb_transport module use for needs other then if_ntb, etc.
Sponsored by: iXsystems, Inc.
Since SBARxSZ register can be write-once, it can be unusable for disabling
the SBAR. For such case also set SBARxBASE to zero to not intersect with
config BAR.
* the code already stored the length of the RX desc, which I never used.
So, use that and retire the new flag I introduced a while ago.
* Introduce a TX timestamp length field and capability.
* extend the TX timestamp to 32 bits, as the AR5416 and later does a full
32 bit TX timestamp instead of 15 or 16 bits.
* add RX descriptor fields for PHY uploaded information (coming soon)
* add flags for RX/TX fast timestamp, hardware upload, etc
* add a flag for TX to request ToD/ToA location information.
Incorrect sign expansion in variables that supposed to be a bit fields
caused infinite loop. Fixing this allows system properly detect maximal
possible 32 devices configured on AHCI HBA of BHyVe. That case did not
happen in a wild before due to lack of hardware AHCI HBAs with 32 ports.
Approved by: re (gjb@)
MFC after: 1 week
mp_maxid or CPU_FOREACH() as appropriate. This fixes a number of places in
the kernel that assumed CPU IDs are dense in [0, mp_ncpus) and would try,
for example, to run tasks on CPUs that did not exist or to allocate too
few buffers on systems with sparse CPU IDs in which there are holes in the
range and mp_maxid > mp_ncpus. Such circumstances generally occur on
systems with SMT, but on which SMT is disabled. This patch restores system
operation at least on POWER8 systems configured in this way.
There are a number of other places in the kernel with potential problems
in these situations, but where sparse CPU IDs are not currently known
to occur, mostly in the ARM machine-dependent code. These will be fixed
in a follow-up commit after the stable/11 branch.
PR: kern/210106
Reviewed by: jhb
Approved by: re (glebius)
Fix the race between ioat_reset_hw and ioat_process_events.
HW reset isn't protected by a lock because it can sleep for a long time
(40.1 ms). This resulted in a race where we would process bogus parts
of the descriptor ring as if it had completed. This looked like
duplicate completions on old events, if your ring had looped at least
once.
Block callout and interrupt work while reset runs so the completion end
of things does not observe indeterminate state and process invalid parts
of the ring.
Start the channel with a manually implemented ioat_null() to keep other
submitters quiesced while we wait for the channel to start (100 us).
r295605 may have made the race between ioat_reset_hw and
ioat_process_events wider, but I believe it already existed before that
revision. ioat_process_events can be invoked by two asynchronous
sources: callout (softclock) and device interrupt. Those could race
each other, to the same effect.
Reviewed by: markj
Approved by: re
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D7097
