Commit Graph

240 Commits

Author SHA1 Message Date
Kevin Lo
128236c022 Remove break after return. 2015-01-23 15:14:30 +00:00
Gleb Smirnoff
c8dfaf382f Mechanically convert to if_inc_counter(). 2014-09-19 03:51:26 +00:00
Gleb Smirnoff
1bffa9511f Use define from if_var.h to access a field inside struct if_data,
that resides in struct ifnet.

Sponsored by:	Nginx, Inc.
2014-08-30 19:55:54 +00:00
John Baldwin
068d8643ad Fix various NIC drivers to properly cleanup static DMA resources.
In particular, don't check the value of the bus_dma map against NULL
to determine if either bus_dmamem_alloc() or bus_dmamap_load() succeeded.
Instead, assume that bus_dmamap_load() succeeeded (and thus that
bus_dmamap_unload() should be called) if the bus address for a resource
is non-zero, and assume that bus_dmamem_alloc() succeeded (and thus
that bus_dmamem_free() should be called) if the virtual address for a
resource is not NULL.

In many cases these bugs could result in leaks when a driver was detached.

Reviewed by:	yongari
MFC after:	2 weeks
2014-06-11 14:53:58 +00:00
Gleb Smirnoff
76039bc84f The r48589 promised to remove implicit inclusion of if_var.h soon. Prepare
to this event, adding if_var.h to files that do need it. Also, include
all includes that now are included due to implicit pollution via if_var.h

Sponsored by:	Netflix
Sponsored by:	Nginx, Inc.
2013-10-26 17:58:36 +00:00
Gleb Smirnoff
c6499eccad Mechanically substitute flags from historic mbuf allocator with
malloc(9) flags in sys/dev.
2012-12-04 09:32:43 +00:00
Dimitry Andric
29658c96ce Remove duplicate const specifiers in many drivers (I hope I got all of
them, please let me know if not).  Most of these are of the form:

static const struct bzzt_type {
	[...list of members...]
} const bzzt_devs[] = {
	[...list of initializers...]
};

The second const is unnecessary, as arrays cannot be modified anyway,
and if the elements are const, the whole thing is const automatically
(e.g. it is placed in .rodata).

I have verified this does not change the binary output of a full kernel
build (except for build timestamps embedded in the object files).

Reviewed by:	yongari, marius
MFC after:	1 week
2012-11-05 19:16:27 +00:00
Marius Strobl
e4029d4cac - Change the module order of these MAC drivers to be last so they are
deterministically handled after the corresponding PHY drivers when
  loaded as modules. Otherwise, when these MAC/PHY driver pairs are
  compiled into a single module probing the PHY driver may fail. This
  makes r151438 and r226154 actually work. [1]
  Reported and tested by: yongari (fxp(4))
- Use DEVMETHOD_END.
- Use NULL instead of 0 for pointers.

Submitted by:	jhb [1]
MFC after:	3 days
2012-05-11 02:40:40 +00:00
Marius Strobl
4b7ec27007 - There's no need to overwrite the default device method with the default
one. Interestingly, these are actually the default for quite some time
  (bus_generic_driver_added(9) since r52045 and bus_generic_print_child(9)
  since r52045) but even recently added device drivers do this unnecessarily.
  Discussed with: jhb, marcel
- While at it, use DEVMETHOD_END.
  Discussed with: jhb
- Also while at it, use __FBSDID.
2011-11-22 21:28:20 +00:00
Marius Strobl
166e31d988 - There's no need to ignore the return value of mii_attach(9) when attaching
dcphy(4) (CID 9283).
- In dc_detach(), check whether ifp is NULL as dc_attach() may call the
  former without ifp being allocated (CID 4288).

Found with:	Coverity Prevent(tm)
2011-11-18 21:22:43 +00:00
Pyun YongHyeon
89b2411bc3 Partially revert r218788. r218788 removed calling dc_setcfg() for
!DC_IS_ADMTEK in dc_miibus_statchg(). This change broke link
establishment of Intel 21143 with dcphy(4) where it stuck in
"ability detect" state without completing auto-negotiation.
Also nuke dc_if_media as it's not actually used.

Submitted by:	marius
2011-11-18 19:38:19 +00:00
Marius Strobl
8c1093fc50 - Import the common MII bitbang'ing code from NetBSD and convert drivers to
take advantage of it instead of duplicating it. This reduces the size of
  the i386 GENERIC kernel by about 4k. The only potential in-tree user left
  unconverted is xe(4), which generally should be changed to use miibus(4)
  instead of implementing PHY handling on its own, as otherwise it makes not
  much sense to add a dependency on miibus(4)/mii_bitbang(4) to xe(4) just
  for the MII bitbang'ing code. The common MII bitbang'ing code also is
  useful in the embedded space for using GPIO pins to implement MII access.
- Based on lessons learnt with dc(4) (see r185750), add bus barriers to the
  MII bitbang read and write functions of the other drivers converted in
  order to ensure the intended ordering. Given that register access via an
  index register as well as register bank/window switching is subject to the
  same problem, also add bus barriers to the respective functions of smc(4),
  tl(4) and xl(4).
- Sprinkle some const.

Thanks to the following testers:
Andrew Bliznak (nge(4)), nwhitehorn@ (bm(4)), yongari@ (sis(4) and ste(4))
Thanks to Hans-Joerg Sirtl for supplying hardware to test stge(4).

Reviewed by:	yongari (subset of drivers)
Obtained from:	NetBSD (partially)
2011-11-01 16:13:59 +00:00
Pyun YongHyeon
52ca7ee210 Add support for ALi/ULi, now NVIDIA, M5261/M5263 PCI FastEthernet
controller which is found on ULi M1563 South Bridge & M1689 Bridge.
These controllers look like a tulip clone.
M5263 controller does not support MII bitbang so use DC_ROM
register to access MII registers.  Like other tulip variants, ULi
controller uses a setup frame to configure RX filter and uses new
setup frame format.  It's not clear to me whether the controller
supports a hash based multicast filtering so this patch uses 14
perfect multicast filter to filter multicast frames.  If number of
multicast addresses is greater than 14, controller is put into a
mode that receives all multicast frames.
Due to lack of access to M5261, this change was not tested with
M5261 but it probably works.  Many thanks to Marco who provided
remote access to M5263.

Tested by:	Marco Steinbach <coco <> executive-computing dot de>,
		Martin MATO <martin.mato <> orange dot fr>
2011-10-24 20:48:02 +00:00
Pyun YongHyeon
d7e9ac7523 When driver is run for the first time there would be no established
link such that calling dc_setcfg() right after media change would
be meaningless unless controller in question is not Davicom DM9102.
Ideally dc_setcfg() should be called when speed/duplex is resolved
otherwise it would reprogram controller with wrong speed/duplex
information.  Because MII status change callback already calls
dc_setcfg() I think calling dc_setcfg() in dc_init_locked() is
wrong.  For instance, it would take some time to establish a link
after mii_mediachg(), so blindly calling dc_setcfg() right after
mii_mediachg() will always yield wrong media configuration.

Extend dc_ifmedia_upd() to handle media change and still allow
21143 and Davidcom controllers program speed/duplex regardless of
current resolved speed/duplex of link. In theory 21143 may not need
to call dc_setcfg() right after media change, but leave it as it is
because there are too many variants to test that change.  Probably
dc(4) shall need a PHY reset in dc_ifmedia_upd() but it's hard to
verify correctness of the change.

This change reliably makes ULi M5263 establish a link.

While I'm here correctly report media change result. Previously it
always reported a success.
2011-10-24 20:26:37 +00:00
Pyun YongHyeon
8c094ecc83 Add missing bus_dmamap_sync() in setup frame transmit.
MFC after:	3 days
2011-10-24 17:09:22 +00:00
Pyun YongHyeon
cb94db27d2 Fix a regression introduced in r218832. For TX status check, driver
should use a TX list DMA tag.

MFC after:	3 days
2011-10-24 17:05:59 +00:00
Warner Losh
7a6fab6656 Supress command completion failure warning when the card isn't
present.  Only call the bus to check if we actually do timeout so we
don't affect the normal case (since this case needn't be optimized and
this guards against all races).
2011-06-21 20:52:55 +00:00
Pyun YongHyeon
1da7683a7c Revise r220046 by introducing dc_netcfg_wait() which waits the end
of active DMA cycle. dc_setcfg() also has to wait until the DMA
engine is stopped so using a common function to handle the job is
better than duplicating the code.

No objection from:	marius
2011-03-28 19:08:53 +00:00
Marius Strobl
f7c719b1b3 Wait until the DMA engine is stopped before unmapping buffers and
descriptors, which fixes DMA errors seen on sparc64.

Obtained from:	OpenBSD
MFC after:	1 week
2011-03-26 22:39:23 +00:00
Pyun YongHyeon
848a02fc41 Remove too expensive bus_dmamap_sync(9) call in dc_rx_resync().
With this change, driver may not notice updated descriptor status
change when bounce buffers are active. However, rxeof() in next run
will handle the synchronization.

Change dc_rxeof() a bit to return the number of processed frames in
RX descriptor ring. Previously it returned the number of frames
that were successfully passed to upper stack which in turn means it
ignored frames that were discarded due to errors. The number of
processed frames in RX descriptor ring is used to detect whether
driver is out of sync with controller's current descriptor pointer.
Returning number of processed frames reduces unnecessary (probably
wrong) re-synchronization.

Reviewed by:	marius
2011-03-16 17:09:51 +00:00
Pyun YongHyeon
d9efae0351 Rearrange dc_tx_underrun() a bit to correctly set TX FIFO threshold
value. Controllers that always require "store and forward" mode(
Davicom and PNIC 82C168) have no way to recover from TX underrun
except completely reinitializing hardware. Previously only Davicom
was reinitialized and the TX FIFO threshold was changed not to use
"store and forward" mode after reinitialization since the default
FIFO threshold value was 0. This effectively disabled Davicom
controller's "store and forward" mode once it encountered TX
underruns. In theory, this can cause watchodg timeouts.

Intel 21143 controller requires TX MAC should be idle before
changing TX FIFO threshold. So driver tried to disable TX MAC and
checked whether it saw the idle state of TX MAC. Driver should
perform full hardware reinitialization on failing to enter to idle
state and it should not touch TX MAC again once it performed full
reinitialization.

While I'm here remove resetting TX FIFO threshold to 0 when
interface is put into down state. If driver ever encountered TX
underrun, it's likely to trigger TX underrun again whenever
interface is brought to up again. Keeping old/learned TX FIFO
threshold value shall reduce the chance of seeing TX underrns in
next run.
2011-03-08 19:49:16 +00:00
Pyun YongHyeon
8f382a1fd0 Remove unnecessary controller reinitialization which resulted in
link flips during alias address insertion or dhclient operation.
While I'm here remove dc_reset() in DC_ISR_BUS_ERR case. Device is
fully reinitialized again in dc_init_locked().
2011-02-23 02:40:31 +00:00
Pyun YongHyeon
ee320f98a9 s/u_intXX_t/uintXX_t/g 2011-02-19 03:32:10 +00:00
Pyun YongHyeon
e4eb0f2e15 Consistently use a tab character instead of space after #define.
No functional changes.
2011-02-19 03:23:19 +00:00
Pyun YongHyeon
26b40a6592 Count how many frames driver lost in interrupt handler. This
register is cleared on read so make sure to clear it in driver
initialization phase.
2011-02-19 03:01:24 +00:00
Pyun YongHyeon
5f14ee2363 Split common TX/RX descriptor DMA tag to TX and RX DMA tags
respectively and fix all bus_dma(9) issues seen when bounce buffers
are used.
 o Setup frame handling had no bus_dmamap_sync(9) which prevented
   driver from configuring RX filter. Add missing bus_dmamap_sync(9)
   in both dc_setfilt_21143()/dc_setfilt_xircom() and dc_txeof().
 o Use bus_addr_t for DMA segment instead of using u_int32_t.
 o Introduce dc_dma_alloc()/dc_dma_free() functions to allocate/free
   DMA'able memory.
 o Create two DMA descriptor list for each TX/RX lists. This change
   will minimize the size of bounce buffers that would be used in
   each TX/RX path.  Previously driver had to copy both TX/RX lists
   when bounce buffer is active.
 o 21143 data sheet says descriptor list requires 4 bytes alignment.
   Remove PAGE_SIZE alignment restriction and use
   sizeof(struct dc_dec).
 o Setup frame requires 4 bytes alignment.  Remove PAGE_SIZE
   alignment restriction and use sizeof(struct dc_dec).
 o Add missing DMA map unload for both setup frame and TX/RX
   descriptor list.
 o Overhaul RX handling logic such that make driver always allocate
   new RX buffer with dc_newbuf(). Previously driver allowed to
   copy received frame with m_devget(9) after passing the
   descriptor ownership to controller. This can lead to passing
   wrong frame to upper stack.
 o Introduce dc_discard_rxbuf() which will discard received frame
   and reuse loaded DMA map and RX mbuf.
 o Correct several wrong bus_dmamap_sync(9) usage in dc_rxeof and
   dc_txeof. The TX/RX descriptor lists are updated by both driver
   and HW so READ/WRITE semantics should be used.
 o If driver failed to allocate new RX buffer, update if_iqdrops
   counter instead of if_ierrors since driver received the frame
   without errors.
 o Make sure to unload loaded setup frame DMA map in dc_txeof and
   clear the mark of setup frame of the TX descriptor in dc_txeof().
 o Add check for possible TX descriptor overruns in dc_encap() and
   move check for free buffer to caller, dc_start_locked().
 o Swap the loaded DMA map and the last DMA map for multi-segmented
   frames. Since dc_txeof() assumes the last descriptor of the
   frame has the DMA map, driver should swap the first and the last
   DMA map in dc_encap(). Previously driver tried to unload
   not-yet-loaded DMA map such that the loaded DMA map was not
   unloaded at all for multi-segmented frames.
 o Rewrite DC_RXDESC/DC_TXDESC macro to simpler one.
 o Remove definition of ETHER_ALIGN, it's already defined in
   ethernet.h.

With this changes, dc(4) works with bounce buffers and it shall
also fix issues which might have shown in PAE environments.

Tested by:	marius
2011-02-19 02:47:10 +00:00
Pyun YongHyeon
a84b4e80ca Rearrange interrupt handler a bit and remove forever loop.
Previously dc(4) always checked whether there is pending interrupts
and this consumed a lot of CPU cycles in interrupt handler. Limit
the number of processing for TX/RX frames to 16. Also allow sending
frames in the loop not to starve TX under high RX load.
Reading DC_ISR register should be protected with driver lock,
otherwise interrupt handler could be run(e.g. link state change)
before the completion of dc_init_locked().

While I'm here remove unneeded code.
2011-02-19 01:37:28 +00:00
Pyun YongHyeon
76d40c8593 Send frames only when there is a valid link and driver is running
as well as controller has enough free TX descriptors.
Remove check for number of queued frames before attempting to
transmit. I guess it was added to allow draining queued frames
even if there is no link. I'm under the impression this type of
check should be done in upper layer. No other drivers in tree do
that.
2011-02-19 00:00:32 +00:00
Pyun YongHyeon
a5db292f7b Fix a long standing bug where driver handed over RX descriptor
ownership to controller before completion of access to the
descriptor. Driver is faking up status word so it should not give
ownership to controller until it completes RX processing.
2011-02-18 23:18:08 +00:00
Pyun YongHyeon
24507bc168 There is no need to execute filter configuration when driver is not
running. Remove wrong driver state change in dc_setfilt_xircom().
While I'm here nuke unnecessary assignments.
2011-02-18 23:08:05 +00:00
Pyun YongHyeon
52c43a473e Make sure to clear status word of TX descriptor in dc_list_tx_init().
Do not update if_opackets if the transmission had failed.
2011-02-18 22:58:46 +00:00
Pyun YongHyeon
06d23883e7 For controllers that have TX interrupt moderation capability,
request TX completion interrupt for every 8-th frames. Previously
dc(4) requested TX completion interrupt if number of queued TX
descriptors is greater than 64. This caused a lot of TX completion
interrupt under high TX load once driver queued more than 64 TX
descriptors. It's quite normal to see more than 64 queued TX
descriptors under high TX load.
This change reduces the number of TX completion interrupts to be
less than 17k under high TX load. Because this change does not
generate TX completion interrupt for each frame, add reclaiming
transmitted buffers in dc_tick not to generate false watchdog
timeouts.
While I'm here add check for queued descriptors in dc_txeof() since
there is no more work to do when there is no pending descriptors.
2011-02-18 20:38:05 +00:00
Pyun YongHyeon
93856bdece Remove use case of DC_TX_ONE. It was used to limit queue just 1 TX
frame in DM910x controllers. In r67595(more than 10 years ago) it
was replaced to use "Store and Forward" mode and made controller
generate TX completion interrupt for every frame.
2011-02-18 03:37:53 +00:00
Pyun YongHyeon
d314ebf548 Apply special PHY initialization code for 21143 controllers before
any other media configuration. Otherwise some 21143 controller
cannot establish a link. While I'm here remove the PHY
initialization code in dc_setcfg(). Since dc_setcfg() is called
whenever link state is changed, having the PHY initialization code
in dc_setcfg() resulted in continuous link flips.
After driver resets SIA, use default SIA transmit/receive
configuration instead of disabling autosense/autonegotiation.
Otherwise, controller fails to establish a link as well as losing
auto-negotiation capability. For manual media configuration, always
configure 21143 controller with specified media to ensure media
change. This change makes ANA-6922 establish link with/without
auto-negotiation.

While I'm here be more strict on link UP/DOWN detection logic.

Many thanks to marius who fixed several bugs in initial patch and
even tested the patch on a couple of dc(4) controllers.

PR:		kern/79262
Reviewed by:	marius
Tested by:	marius
2011-02-18 02:58:09 +00:00
Pyun YongHyeon
b289c60720 When driver have to use base softc due to lack of SROM on second
port, copy SROM information from base softc as well and run SROM
parser again.  This change is necessary for some dual port
controllers to make dc(4) correctly detect PHY media based on first
port configuration table.
While I'm here add a check for validity of the base softc before
duplicating SROM contents from base softc. If driver failed to
attach to the first port it can access invalid area.

PR:		kern/79262
Reviewed by:	marius
2011-02-18 02:14:53 +00:00
Pyun YongHyeon
abe4e86598 Always check memory allocation failure. If driver encounter memory
allocation error, do not attach driver.

Reviewed by:	marius
2011-02-18 01:56:25 +00:00
Marius Strobl
8e5d93dbb4 Convert the PHY drivers to honor the mii_flags passed down and convert
the NIC drivers as well as the PHY drivers to take advantage of the
mii_attach() introduced in r213878 to get rid of certain hacks. For
the most part these were:
- Artificially limiting miibus_{read,write}reg methods to certain PHY
  addresses; we now let mii_attach() only probe the PHY at the desired
  address(es) instead.
- PHY drivers setting MIIF_* flags based on the NIC driver they hang
  off from, partly even based on grabbing and using the softc of the
  parent; we now pass these flags down from the NIC to the PHY drivers
  via mii_attach(). This got us rid of all such hacks except those of
  brgphy() in combination with bce(4) and bge(4), which is way beyond
  what can be expressed with simple flags.

While at it, I took the opportunity to change the NIC drivers to pass
up the error returned by mii_attach() (previously by mii_phy_probe())
and unify the error message used in this case where and as appropriate
as mii_attach() actually can fail for a number of reasons, not just
because of no PHY(s) being present at the expected address(es).

Reviewed by:	jhb, yongari
2010-10-15 14:52:11 +00:00
Pyun YongHyeon
39d76ed635 It seems some multi-port dc(4) controllers shares SROM of the first
port such that reading station address from second port always
returned 0xFF:0xFF:0xFF:0xFF:0xFF:0xFF Unfortunately it seems there
is no easy way to know whether SROM is shared or not. Workaround
the issue by traversing dc(4) device list and see whether we're
using second port and use station address of controller 0 as base
station address of second port.

PR:		kern/79262
MFC after:	2 weeks
2010-10-14 17:22:38 +00:00
Warner Losh
a2d61e43c2 Fix CardBus spelling.
MFC after:	1 month
2010-01-03 23:15:14 +00:00
Martin Blapp
593a1aea1a Fix card/device names, no functional change
The ADMtek AN985 is the cardbus variant of ADMtek AN983
The Netgear FA511 is just a relabled ADMtek AN985

PR:		kern/50574
MFC after:	1 month
2010-01-03 13:59:59 +00:00
Robert Watson
eb956cd041 Use if_maddr_rlock()/if_maddr_runlock() rather than IF_ADDR_LOCK()/
IF_ADDR_UNLOCK() across network device drivers when accessing the
per-interface multicast address list, if_multiaddrs.  This will
allow us to change the locking strategy without affecting our driver
programming interface or binary interface.

For two wireless drivers, remove unnecessary locking, since they
don't actually access the multicast address list.

Approved by:	re (kib)
MFC after:	6 weeks
2009-06-26 11:45:06 +00:00
Attilio Rao
1abcdbd127 When user_frac in the polling subsystem is low it is going to busy the
CPU for too long period than necessary.  Additively, interfaces are kept
polled (in the tick) even if no more packets are available.
In order to avoid such situations a new generic mechanism can be
implemented in proactive way, keeping track of the time spent on any
packet and fragmenting the time for any tick, stopping the processing
as soon as possible.

In order to implement such mechanism, the polling handler needs to
change, returning the number of packets processed.
While the intended logic is not part of this patch, the polling KPI is
broken by this commit, adding an int return value and the new flag
IFCAP_POLLING_NOCOUNT (which will signal that the return value is
meaningless for the installed handler and checking should be skipped).

Bump __FreeBSD_version in order to signal such situation.

Reviewed by:	emaste
Sponsored by:	Sandvine Incorporated
2009-05-30 15:14:44 +00:00
Warner Losh
155a83e87a remove now-redunant cardbus attachment. 2009-03-09 13:23:54 +00:00
Marius Strobl
155781198a - According to the corresponding Linux, NetBSD and OpenSolaris
drivers, there should be a 1us delay after every write when
  bit-banging the MII. Also insert barriers in order to ensure
  the intended ordering. These changes hopefully will solve the
  bus wedging occasionally experienced with DM9102A since r182461.
- Deobfuscate dc_mii_readreg() a bit.
2008-12-07 23:02:37 +00:00
Marius Strobl
d0d67284f8 For chips with a broken DC_ISR_RX_STATE which f.e. never signals
stopped nor the waiting state and also no other means to check
whether the receiver is idle (see also r163774), we have no choice
than to call mii_tick(9) unconditionally even in the case of the
DC_REDUCED_MII_POLL handling as far as the RX side is concerned.
This isn't necessarily worse than checking whether RX is idle
though because unlike as with TX we're racing with the hardware,
which might receive packets any time while we poll the MII, anyway.

Reported and tested by:	Jacob Owens
Reviewed by:		yongari
MFC after:		3 days
2008-08-29 20:31:41 +00:00
Marius Strobl
993a741ac6 - Use m_collapse(9) instead of m_defrag(9) if possible. This results
in a noticeable reduction in system time spent.
- If bus_dmamap_load_mbuf_sg(9) fails with EFBIG and we already have
  defragmented the mbuf chain, don't bother to defragment and load it
  a second time just yet as it's likely to fail again anyway.

MFC after:	3 days
2008-08-23 20:57:48 +00:00
Pyun YongHyeon
2e3d4b798b Ethernet hardware address stored in DC_AL_PAR0/DC_AL_PAR1 register
is in little endian form. Likewise setting DC_AL_PAR0/DC_AL_PAR1
register expect the address to be in little endian form. For big
endian architectures the address should be swapped to get correct
one.
Change setting/getting ethernet hardware address to big endian
architecture frendly.

Reported by:	Robert Murillo ( billypilgrim782001 at yahoo dot com )
Tested by:	Robert Murillo ( billypilgrim782001 at yahoo dot com )
2008-06-08 02:52:26 +00:00
Marius Strobl
ebc284cc83 - Const'ify the dc_devs array.
- Correct the maxsize parameter when creating the mbufs busdma tag to
  reflect the actual requirement of dc(4).
- Move the KASSERT in dc_newbuf() to the right spot.
- Also convert the TX side to take advantage of bus_dmamap_load_mbuf_sg(9).
- Move the comment regarding dc_start_locked() to the right spot.

MFC after:	2 weeks
2008-03-24 17:38:24 +00:00
Pyun YongHyeon
6a087a8722 Fix function prototype for device_shutdown method. 2007-11-22 02:45:00 +00:00
Marius Strobl
82a67a70a2 o In order to reduce bug and code duplication fold handling of NICs
requiring DC_TX_ALIGN or DC_TX_COALESCE, which was previously done
  in dc_start_locked(), into dc_encap().
o In dc_encap():
  - If m_defrag() fails just drop the packet like other NIC drivers
    do. This should only happen when there's a mbuf shortage, in which
    case it was possible to end up with an IFQ full of packets which
    couldn't be processed as they couldn't be defragmented as they
    were taking up all the mbufs themselves. This includes adjusting
    dc_start_locked() to not trying to prepend the mbuf (chain) if
    dc_encap() has freed it.
  - Likewise, if bus_dmamap_load_mbuf() fails as dc_dma_map_txbuf()
    failed, free the mbuf possibly allocated by the above call to
    m_defrag() and drop the packet.
o In dc_txeof():
  - Don't clear IFF_DRV_OACTIVE unless there are at least 6 free TX
    descriptors. Further down the road dc_encap() will bail if there
    are only 5 or fewer free TX descriptors, causing dc_start_locked()
    to abort and prepend the dequeued mbuf again so it makes no sense
    to pretend we could process mbufs again when in fact we won't.
    While at it replace this magic 5 with a macro DC_TX_LIST_RSVD.
  - Just always assign idx to sc->dc_cdata.dc_tx_cons; it doesn't
    make much sense to exclude the idx == sc->dc_cdata.dc_tx_cons
    case.
o In dc_dma_map_txbuf() there's no need to set sc->dc_cdata.dc_tx_err
  to error if the latter is != 0, bus_dmamap_load_mbuf() already
  returns the same error value in that case anyway.
o For less overhead, convert to use bus_dmamap_load_mbuf_sg() for
  loading RX buffers.
o Remove some banal and/or outdated comments.

Approved by:	re (kensmith)
MFC after:	1 week
2007-08-05 11:28:19 +00:00