dirty and murky past.
* Override the default cache line size to be something reasonable if
it's set to 0. Some NICs initialise with '0' (eg embedded ones)
and there are comments in the driver stating that various OSes (eg
older Linux ones) would incorrectly program things and 0 out this
register.
* Just default to overriding the latency timer. Every other driver
does this.
* Use a default cache line size of 32 bytes. It should be "reasonable
enough".
Obtained from: Linux ath9k, Atheros
interface.
* Introduce a device hint, 'eeprom_firmware', which is the name of firmware
to lookup.
* If the lookup succeeds, take a copy of it and use it as the eeprom data.
This isn't enabled by default - you have to define ATH_EEPROM_FIRMWARE.
I'll add it to the configuration variables in a later commit.
TODO:
* just keep a firmware reference in ath_softc, and remove the need to
waste the extra memory in having sc_eepromdata be a malloc()ed block.
add a FreeBSD_version check. It should work fine for compiling
on -HEAD, 9.x and 8.x.
* Conditionally compile the 11n options only when 11n is enabled.
The above changes allow the ath(4) driver to compile and run on
8.1-RELEASE (Hi old PC-BSD!) but with the 11n stuff disabled.
I've done a test against the net80211 and tools in 8.1-RELEASE.
The NIC used in testing is the AR2427 in an EEEPC.
Just to be clear - this change is to allow the -HEAD ath/hal/rate
code to run on 9.x _and_ 8.x with no source changes. However,
when running on earlier kernels, it should only be used for legacy
mode. (Don't define ATH_ENABLE_11N.)
damage which I committed when I had less clue about such things.
Don't ever put normal data frames on the mcast software queue.
Just put mcast frames there if needed.
Pass the txq decision into ath_tx_normal_setup(), as we've already made
the decision. Don't re-do it.
Whilst i'm here, add another random debugging statement.
call these after rate control selection is done.
The duration/protection code wasn't working - it expected the rix to
be valid. Unfortunately after I moved the rate control selection into
late in the process, the rix value isn't valid and thus the protection/
duration code would get things wrong.
HT frames are now correctly protected with an RTS and for the AR5416,
this involves having the aggregate frames be limited to 8K.
TODO:
* Fix up the DMA sync to occur just before the frame is queued to the
hardware. I'm adjusting the duration here but not doing the DMA
flush.
* Doubly/triply ensure that the aggregate frames are being limited to
the correct size, or the AR5416 will get unhappy when TXing RTS-protected
aggregates.
if any subframes in an aggregate have different protection from the
first frame in the formed aggregate, don't add that frame to the
aggregate.
This is likely a suboptimal method (I think we'll mostly be OK marking
frames that have seqno's with the same protection as normal data frames)
but I'll just be cautious for now.
This will be used by some upcoming code to ensure that aggregates
are enforced to be a certain size. The AR5416 has a limitation on
RTS protected aggregates (8KiB).
A BAR frame must be transmitted when an frame in an A-MPDU session fails
to transmit - it's retried too often, or it can't be cloned for
re-transmission. The BAR frame tells the remote side to advance the
left edge of the block-ack window (BAW) to a new value.
In order to do this:
* TX for that particular node/TID must be paused;
* The existing frames in the hardware queue needs to be completed, whether
they're TXed successfully or otherwise;
* The new left edge of the BAW is then communicated to the remote side
via a BAR frame;
* Once the BAR frame has been sucessfully TXed, aggregation can resume;
* If the BAR frame can't be successfully TXed, the aggregation session
is torn down.
This is a first pass that implements the above. What needs to be done/
tested:
* What happens during say, a channel reset / stuck beacon _and_ BAR
TX. It _should_ be correctly buffered and retried once the
reset has completed. But if a bgscan occurs (and they shouldn't,
grr) the BAR frame will be forcibly failed and the aggregation session
will be torn down.
Yes, another reason to disable bgscan until I've figured this out.
* There's way too much locking going on here. I'm going to do a couple
of further passes of sanitising and refactoring so the (re) locking
isn't so heavy. Right now I'm going for correctness, not speed.
* The BAR TX can fail if the hardware TX queue is full. Since there's
no "free" space kept for management frames, a full TX queue (from eg
an iperf test) can race with your ability to allocate ath_buf/mbufs
and cause issues. I'll knock this on the head with a subsequent
commit.
* I need to do some _much_ more thorough testing in hostap mode to ensure
that many concurrent traffic streams to different end nodes are correctly
handled. I'll find and squish whichever bugs show up here.
But, this is an important step to being able to flip on 802.11n by default.
The last issue (besides bug fixes, of course) is HT frame protection and
I'll address that in a subsequent commit.
Linux ath9k doesn't have this issue as it doesn't try queuing multi-
descriptor frames to the hardware.
Before, I was only setting the first and last descriptor in the final
frame correctly - and that was done by accident. The first descriptor in
the last sub-frame was being correctly updated by ath_tx_setds_11n();
the last descriptor in the last sub-frame was being correctly updated
by ath_buf_set_rate(). But both of those are "incorrect".
The correct behaviour is:
* AR_IsAggr is set for all descriptors for all subframes in an aggregate.
* AR_MoreAggr is set for all descriptors for all non-final sub-frames
in an aggregate.
Ie, all descriptors in the last sub-frame of an aggregate must have this
field set to 0.
I still need to do a couple of extra passes to ensure the pad delimiter
field is being correctly handled in all descriptors in the last sub-frame.
Right now ath_txq_sched() is mainly called from the TX ath_tx_processq()
routine, which is (mostly) done as part of the taskqueue. It shouldn't
be called outside the taskqueue.
But now that I'm about to flip back on BAR TX, I'm going to start
stressing the ath_tx_tid_pause() and ath_tx_tid_resume() paths.
What I don't want to have happen is a reschedule of the TID traffic
_during_ the completion of TX frames.
Ideally I'd like to have a way to flag back up to the processing code
that the current hardware queue should be rechecked for software TID
queue frames. But for now, this should suffice for the BAR TX case.
I may eventually delete this code once I've brought some further
sanity to the general TX queue/completion path.
within the BAW.
This regression was introduced in ane earlier commit by me to fix the
BAW seqno allocation-but-not-insertion-into-BAW race. Since it was only
ever using the to-be allocated sequence number, any frame retries
with the first frame in the BAW still in the software queue would
have constantly failed, as ni_txseqs[tid] would always be outside
the BAW.
TODO:
* Extract out the mostly common code here in the agg and non-agg ADDBA
case and stuff it into a single function.
PR: kern/166357
I see traffic stalls.
It turns out that the bug isn't because the first and last frame in the
BAW is in the software queue. It is more likely that it's because
the first frame in the BAW is still in the software queue and thus there's
no more room to allocate and do subsequent TX.
PR: kern/166357
This is not entirely correct as it simply resets the channel, flushing
whatever is in the TX/RX queue. This can and will break aggregation
BAW tracking. But the alternative (HT40 frames being sent with the hardware
in HT20 mode) is even worse.
There's still a small window between the htinfo being received (and the ni_chw
field being updated) which could cause problems. I'll look at fleshing this
out in follow-up commits.
PR: kern/166286
is queued to the hardware.
Because multiple concurrent paths can execute ath_start(), multiple
concurrent paths can push frames into the software/hardware TX queue
and since preemption/interrupting can occur, there's the possibility
that a gap in time will occur between allocating the sequence number
and queuing it to the hardware.
Because of this, it's possible that a thread will have allocated a
sequence number and then be preempted by another thread doing the same.
If the second thread sneaks the frame into the BAW, the (earlier) sequence
number of the first frame will be now outside the BAW and will result
in the frame being constantly re-added to the tail of the queue.
There it will live until the sequence numbers cycle around again.
This also creates a hole in the RX BAW tracking which can also cause
issues.
This patch delays the sequence number allocation to occur only just before
the frame is going to be added to the BAW. I've been wanting to do this
anyway as part of a general code tidyup but I've not gotten around to it.
This fixes the PR.
However, it still makes it quite difficult to try and ensure in-order
queuing and dequeuing of frames. Since multiple copies of ath_start()
can be run at the same time (eg one TXing process thread, one TX completion
task/one RX task) the driver may end up having frames dequeued and pushed
into the hardware slightly/occasionally out of order.
And, to make matters more annoying, net80211 may have the same behaviour -
in the non-aggregation case, the TX code allocates sequence numbers
before it's thrown to the driver. I'll open another PR to investigate
this and potentially introduce some kind of final-pass TX serialisation
before frames are thrown to the hardware. It's also very likely worthwhile
adding some debugging code into ath(4) and net80211 to catch when/if this
does occur.
PR: kern/166190
* printf -> device_printf
* print the buffer pointer and sequence number for any buffer that wasn't
correctly tidied up before it was freed. This is to aid in some
current SMP TX debugging stalls.
PR: kern/166190
Although access to the flags to check/set OACTIVE is racy due to how
the default if_start() function works, this should remove any races
with read/modify/write between threads.
don't setup the avp mcast queue.
This is a bit annoying though - it turns out the mcast queue isn't
initialised for STA mode but it's then touched to see whether anything
is in it. That should be fixed in a subsequent commit.
Noticed by: gperez@entel.upc.edu
PR: kern/165895
In a very noisy 2.4GHz environment (with HT/40 enabled, making it worse)
I saw the following occur:
* the air was considered "busy" a lot of the time;
* the cabq time is quite short due to staggered beacons being enabled;
* it just wasn't able to keep up TX'ing CABQ frames;
* .. and the cabq would swallow up all the TX ath_buf's.
This patch introduces a twiddle which allows the maximum cabq depth to be
set, forcing further frames to be dropped.
It defaults to the TX buffer count at the moment, so the default behaviour
isn't changed.
I've also started fleshing out a similar setup for the data path, so
it doesn't swallow up all the available TX buffers and preventing management
frames (such as ADDBA) out.
PR: kern/165895
frames with stations in power saving mode.
I'm not (yet) sure how to handle TX'ing aggregates frames to stations
that are in power saving mode, or whether that's even a feasible thing
to do. So in order to (mostly) not forget, leave a couple of comments
in the code.
The code presently assumes that the aggregation TID state for an ath_node
is locked not by the ath_node lock or a node+TID lock, but behind the
hardware queue said TID maps to. This assumption is going to be
incorrect for stations in power saving mode as we'll be TX'ing frames
on the multicast queue.
In any case, I'm afraid its a "later problem". :/
This function must be called with both the source and destination TXQs
locked or things will get hairy.
I added this as part of some debugging in a PR but it turned out to not
be the cause. I still think it's -correct- so, here it is.
the last buffer in the list.
The current behaviour (due to me, so pointy hat is firmly on my head here)
was incorrect - it was setting the link pointer to the last descriptor
of the _first_ buffer in the TXQ. Instead, it should have set it to the
last descriptor in the _last_ buffer in the TXQ.
This showed up as occasional TX stalls with frames in the TXQ but no
TX progress being made. Further inspection showed the TXQ looked like
it contained multiple "lists" of frames - there'd be a list of correct
frames, then a NULL link pointer, but there'd be a next buffer in the
list.
Since this code is only called upon an interface reset, it's likely
this only began showing up when I started doing stress testing
in environments which annoy the radios enough to cause lockups.
I've not yet any TX stalls with this patch applied.
PR: kern/165866
been bait-and-switched from the rate control code.
This will avoid the panic that I saw and will avoid sending invalid rates
(eg 11a/11g OFDM rates when in 11b, on 11b-only NICs (AR5211)) where the
rate table is not "big".
It also will point out situations where this occurs for the 11n NICs
which will have sufficiently large rate tables that "invalid rix" doesn't
occur.
I'll try to follow this up with a commit that adds a current operating mode
check. The "rix" is only relevant to the current operating mode and rate
table.
PR: kern/165475
* ath_reset() is being called in softclock context, which may have the
thing sleep on a lock. To avoid this, since we really _shouldn't_
be sleeping on any locks, break out the no-loss reset path into a tasklet
and call that from:
+ ath_calibrate()
+ ath_watchdog()
This has the added advantage that it'll end up also doing the frame
RX cleanup from within the taskqueue context, rather than the softclock
context.
* Shuffle around the taskqueue_block() call to be before we grab the lock
and disable interrupts.
The trouble here is that taskqueue_block() doesn't block currently
queued (but not yet running) tasks so calling it doesn't guarantee
no further tasks (that weren't running on _A_ CPU at the time of this
call) will complete. Calling taskqueue_drain() on these tasks won't
work because if any _other_ thread calls taskqueue_enqueue() for whatever
reason, everything gets very angry and stops working.
This slightly changes the race condition enough to let ath_rx_tasklet()
run before we try disabling it, and thus quietens the warnings a bit.
The (more) true solution will be doing something like the following:
* having a taskqueue_blocked mask in ath_softc;
* having an interrupt_blocked mask in ath_softc;
* only calling taskqueue_drain() on each individual task _after_ the
lock has been acquired - that way no further tasklet scheduling
is going to occur.
* Then once the tasks have been blocked _and_ the interrupt has been
disabled, call taskqueue_drain() on each, ensuring that anything
that _was_ scheduled or running is removed.
The trouble is if something calls taskqueue_enqueue() on a task
after taskqueue_blocked() has been called but BEFORE taskqueue_drain()
has been called, ta_pending will be set to 1 and taskqueue_drain()
will sit there stuck in msleep() until you hard-kill the machine.
PR: kern/165382
PR: kern/165220
I'm not sure _why_ the ic is NULL here, but I've seen it occasionally do
this after I've been tinkering with things for a while. It ends up
crashing in a call to ath_chan_set() via the net80211 scan code and scan
task.
