buffers.
ath_descdma is now being used for things other than the classical
combination of ath_buf + ath_desc allocations. In this particular case,
don't try to free and blank out the ath_buf list if it's not passed in.
of buffers, only the number of descriptors.
This involves:
* Change the allocation function to not use nbuf at all;
* When calling it, pass in "nbuf * ndesc" to correctly update how many
descriptors are being allocated.
Whilst here, fix the descriptor allocation code to correctly allocate
a larger buffer size if the Merlin 4KB WAR is required. It overallocates
descriptors when allocating a block that doesn't ever have a 4KB boundary
being crossed, but that can be fixed at a later stage.
The AR9300 and later descriptors are 128 bytes, however I'd like to make
sure that isn't used for earlier chips.
* Populate the TX descriptor length field in the softc with
sizeof(ath_desc)
* Use this field when allocating the TX descriptors
* Pre-AR93xx TX/RX descriptors will use the ath_desc size; newer ones will
query the HAL for these sizes.
* Introduce TX DMA setup/teardown methods, mirroring what's done in
the RX path.
Although the TX DMA descriptor is setup via ath_desc_alloc() /
ath_desc_free(), there TX status descriptor ring will be allocated
in this path.
* Remove some of the TX EDMA capability probing from the RX path and
push it into the new TX EDMA path.
sized TX descriptor.
This is required for the AR93xx EDMA support which requires 128 byte
TX descriptors (which is significantly larger than the earlier
hardware.)
For now, the only module implement is 'sample', and that's only partially
implemented. The main issue here with reusing this structure in userland
is that it uses 'rix' everywhere, which requires the userland code to
have access to the current HAL rate table.
For now, this is a very large work in progress.
Specific details:
* The rate control information is per-node at the moment and wrapped
in a TLV, to ease parsing and backwards compatibility.
* .. but so I can be slack for now, the userland statistics are just
a copy of the kernel-land sample node state.
* However, for now use a temporary copy and change the rix entries
to dot11rate entries to make it slightly easier to eyeball.
Problems:
* The actual rate information table is unfortunately indexed by rix
and it doesn't contain a rate code. So the userland side of this
currently has no way to extract out a mapping.
TODO:
* Add a TLV payload to dump out the rate control table mapping so
'rix' can be turned into a dot11 / MCS rate.
* .. then remove the temporary copy.
TX descriptor link pointers.
This is required for the AR93xx and later chipsets.
The RX path is slightly different - the legacy RX path directly
accesses ath_desc->ds_link for now, however this isn't at all done
for EDMA (FIFO) RX.
Now, for those performing a little software archeology here:
This is all a bit sub-optimal. "struct ath_desc" is only really relevant
for the pre-AR93xx NICs - where ds_link and ds_data is always in the
same location.
The AR93xx and later NICs have different descriptor layouts altogether.
Now, for AR93xx and later NICs, you should never directly reference
ds_link and ds_data, as:
* the RX descriptors don't have either - the data is _after_ the RX
descriptor. They're just one large buffer. There's also no need for
a per-descriptor RX buffer size as they're all fixed sizes.
* the TX descriptors have 4 buffer and 4 length fields _and_ a link
pointer. Each frame takes up one TX FIFO pointer, but it can contain
multiple subframes (either multiple frames in a buffer, and/or
multiple frames in an aggregate/RIFS burst.)
* .. so, when TX frames are queued to a hardware queue, the link
pointer is ONLY for buffers in that frame/aggregate. The next frame
starts in a new FIFO pointer.
* Finally, descriptor completion status is in a different ring.
I'll write something up about that when its time to do so.
This was inspired by Linux ath9k and the reference driver but is a
reimplementation.
Obtained from: Linux ath9k, Qualcomm Atheros
The DMA FIFO chips (AR93xx and later) differ slightly to th elegacy
chips:
* The RX DMA descriptors don't have a ds_link field;
* The TX DMA descriptors have a ds_link field however at a different
offset.
This is a reimplementation based on what the reference driver and ath9k
does.
A subsequent commit will enable it in the TX and beacon paths.
Obtained from: Linux ath9k, Qualcomm Atheros
The AR9003 series NICs implement a separate RX error to signal that a
Keycache miss occured. The earlier NICs would not set the key index
valid bit.
I'll dig into the difference between "no key index bit set" and "keycache
miss".
* wrap the RX proc calls in the RX refcount;
* call the DFS checking, fast frames staging and TX rescheduling if
required.
TODO:
* figure out if I can just make "do TX rescheduling" mean "schedule
TX taskqueue" ?
with fresh descriptors, before handling the frames.
Wrap it all in the RX locks.
Since the FIFO is very shallow (16 for HP, 128 for LP) it needs to be
drained and replenished very quickly. Ideally, I'll eventually move this
RX FIFO drain/fill into the interrupt handler, only deferring the actual
frame completion.
I was setting up the RX EDMA buffer to be 4096 bytes rather than the
RX data buffer portion. The hardware was likely getting very confused
and DMAing descriptor portions into places it shouldn't, leading to
memory corruption and occasional panics.
Whilst here, don't bother allocating descriptors for the RX EDMA case.
We don't use those descriptors. Instead, just allocate ath_buf entries.
the FIFO.
I still see some corner cases where no RX occurs when it should be
occuring. It's quite possible that there's a subtle race condition
somewhere; or maybe I'm not programming the RX queues right.
There's also no locking here yet, so any reset/configuration path
state change (ie, enabling/disabling receive from the ioctl, net80211
taskqueue, etc) could quite possibly confuse things.
* For now, kickpcu should hopefully just do nothing - the PCU doesn't need
'kicking' for Osprey and later NICs. The PCU will just restart once
the next FIFO entry is pushed in.
* Teach "proc" about "dosched", so it can be used to just flush the
FIFO contents without adding new FIFO entries.
* .. and now, implement the RX "flush" routine.
* Re-initialise the FIFO contents if the FIFO is empty (the DP is NULL.)
When PCU RX is disabled (ie, writing RX_D to the RX configuration
register) then the FIFO will be completely emptied. If the software FIFO
is full, then no further descriptors are pushed into the FIFO and
things stall.
This all requires much, much more thorough stress testing.
This is inspired by ath9k and the reference driver, but it's a new
implementation of the RX FIFO handling.
This has some issues - notably the FIFO needs to be reprogrammed when
the chip is reset.
* Add a couple of RX errors;
* Add the spectral scan PHY error code;
* extend the RX flags to be a 16 bit field, rather than an 8 bit field;
* Add a new RX flag.
Obtained from: Qualcomm Atheros
The AR93xx and later chips support two RX FIFO queues - a high and low
priority queue.
For legacy chips, just assume the queues are high priority.
This is inspired by the reference driver but is a reimplementation of
the API and code.
AR93xx receive descriptors.
This isn't entirely complete - the AR93xx and later descriptors
don't have a link/buffer pointer; the descriptor contents just
start.
The RX EDMA support requires a modified approach to the RX descriptor
handling.
Specifically:
* There's now two RX queues - high and low priority;
* The RX queues are implemented as FIFOs; they're now an array of pointers
to buffers;
* .. and the RX buffer and descriptor are in the same "buffer", rather than
being separate.
So to that end, this commit abstracts out most of the RX related functions
from the bulk of the driver. Notably, the RX DMA/buffer allocation isn't
updated, primarily because I haven't yet fleshed out what it should look
like.
Whilst I'm here, create a set of matching but mostly unimplemented EDMA
stubs.
Tested:
* AR9280, station mode
TODO:
* Thorough AP and other mode testing for non-EDMA chips;
* Figure out how to allocate RX buffers suitable for RX EDMA, including
correctly setting the mbuf length to compensate for the RX descriptor
and completion status area.
