DC(4) BSD Programmer's Manual DC(4)NAMEdc - DEC/Intel 21140, 21142, 21143, 21145 and clones 10/100 Ethernet
SYNOPSIS
dc* at pci? dev ? function ?
dc* at cardbus? dev ? function ?
dcphy* at mii? phy ?
nsphy* at mii? phy ?
lxtphy* at mii? phy ?
DESCRIPTION
The dc driver provides support for several PCI, MiniPCI, and CardBus Fast
Ethernet adapters and embedded controllers based on the following chip-
sets:
+ DEC 21140 PCI
+ DEC/Intel 21143 PCI and CardBus
+ Intel 21145 PCI
+ Macronix 98713, 98713A, 98715, 98715A, 98725, 98727, and 98732
+ Davicom DM9100, DM9102, and DM9102A
+ ASIX Electronics AX88140A and AX88141
+ ADMtek AL981 Comet PCI and AN983 Centaur-P PCI
+ ADMtek AN985 Centaur-C CardBus
+ Lite-On 82c168 and 82c169 PNIC
+ Lite-On/Macronix 82c115 PNIC II
+ Xircom X3201-based CardBus
All of these chips have the same general register layout, DMA descriptor
format and method of operation. All of the clone chips are based on the
21143 design with various modifications. (The 21140 is an older version
of the 21143.) The 21143 itself has support for 10baseT, BNC, AUI, MII
and symbol media attachments, 10 and 100Mbps speeds in full or half du-
plex, built-in NWAY autonegotiation and wake on LAN. The 21143 also
offers several receive filter programming options including perfect
filtering, inverse perfect filtering and hash table filtering. The 21145
seems to be 10 MBit/s only and has an additional (unsupported) HomePNA
PHY.
Some clone chips duplicate the 21143 fairly closely while others only
maintain superficial similarities. Some support only MII media attach-
ments. Others use different receiver filter programming mechanisms. At
least one supports only chained DMA descriptors (most support both
chained descriptors and contiguously allocated fixed size rings). Some
chips (especially the PNIC) also have peculiar bugs. The dc driver does
its best to provide generalized support for all of these chipsets in ord-
er to keep special case code to a minimum.
These chips are used by many vendors, which makes it difficult to provide
a complete list of all supported cards. The following NICs are known to
work with the dc driver at this time:
+ Digital DE500-BA 10/100 (21143, non-MII)
+ Built-in DE500-BA on DEC Alpha workstations (21143, non-MII)
+ Built-in Ethernet on LinkSys EtherFast 10/100 Instant GigaDrive
(DM9102, MII)
+ Kingston KNE100TX (21143, MII)
+ D-Link DFE-570TX (21143, MII, quad port)
+ NDC SOHOware SFA110A (98713A)
+ NDC SOHOware SFA110A Rev B4 (98715AEC-C)
+ SVEC PN102-TX (98713)
+ CNet Pro120A (98715A or 98713A) and CNet Pro120B (98715)
+ Compex RL100-TX (98713 or 98713A)
+ LinkSys LNE100TX (PNIC 82c168, 82c169)
+ NetGear FA310-TX Rev. D1, D2 or D3 (PNIC 82c169)
+ Matrox FastNIC 10/100 (PNIC 82c168, 82c169)
+ Kingston KNE110TX (PNIC 82c169)
+ LinkSys LNE100TX v2.0 (PNIC II 82c115)
+ Jaton XpressNet (Davicom DM9102)
+ Alfa Inc GFC2204 (ASIX AX88140A)
+ CNet Pro110B (ASIX AX88140A)
+ LinkSys LNE100TX v4.x (ADMtek AN983 Centaur-P)
+ Xircom CardBus, including RealPort models (Xircom X3201)
+ IBM EtherJet 10/100 CardBus (Intel 21143)
+ Accton EN1217 (98715) and EN2242 (ADMtek Centaur)
+ Mototech ME316 (ADMtek Centaur)
+ Conexant LANfinity RS7112 MiniPCI
The dc driver supports the following media types:
autoselect Enable autoselection of the media type and options. The user
can manually override the autoselected mode by adding media
options to the hostname.if(5) file.
Note: the built-in NWAY autonegotiation on the original PNIC
82c168 chip is horribly broken and is not supported by the
dc driver at this time: the chip will operate in any speed
or duplex mode, however these must be set manually. The ori-
ginal 82c168 appears on very early revisions of the LinkSys
LNE100TX and Matrox FastNIC.
10baseT Set 10Mbps operation. The mediaopt option can also be used
to enable full-duplex operation. Not specifying full duplex
implies half-duplex mode.
100baseTX Set 100Mbps (Fast Ethernet) operation. The mediaopt option
can also be used to enable full-duplex operation. Not speci-
fying full duplex implies half-duplex mode.
The dc driver supports the following media options:
full-duplex Force full duplex operation. The interface will operate in
half duplex mode if this media option is not specified.
Note that the 100baseTX media type may not be available on certain Intel
21143 adapters which support 10Mbps media attachments only. The Intel
21145 supports 10 MBit/s half-duplex only. For more information on confi-
guring this device, see ifconfig(8).
DIAGNOSTICS
dc%d: couldn't map ports/memory A fatal initialization error has oc-
curred.
dc%d: couldn't map interrupt A fatal initialization error has occurred.
dc%d: watchdog timeout A packet was queued for transmission and a
transmit command was issued, however the device failed to acknowledge the
transmission before a timeout expired. This can happen if the device is
unable to deliver interrupts for some reason, or if there is a problem
with the network connection (cable).
dc%d: no memory for rx list The driver failed to allocate an mbuf for
the receiver ring.
dc%d: TX underrun -- increasing TX threshold The device generated a
transmit underrun error while attempting to DMA and transmit a packet.
This happens if the host is not able to DMA the packet data into the
NIC's FIFO fast enough. The driver will dynamically increase the transmit
start threshold so that more data must be DMAed into the FIFO before the
NIC will start transmitting it onto the wire.
dc%d: TX underrun -- using store and forward mode The device continued
to generate transmit underruns even after all possible transmit start
threshold settings had been tried, so the driver programmed the chip for
store and forward mode. In this mode, the NIC will not begin transmission
until the entire packet has been transferred into its FIFO memory.
dc%d: chip is in D3 power state -- setting to D0 This message applies
only to adapters which support power management. Some operating systems
place the controller in low power mode when shutting down, and some PCI
BIOSes fail to bring the chip out of this state before configuring it.
The controller loses all of its PCI configuration in the D3 state, so if
the BIOS does not set it back to full power mode in time, it won't be
able to configure it correctly. The driver tries to detect this condition
and bring the adapter back to the D0 (full power) state, but this may not
be enough to return the driver to a fully operational condition. If you
see this message at boot time and the driver fails to attach the device
as a network interface, you will have to perform a second warm boot to
have the device properly configured.
Note that this condition only occurs when warm booting from another
operating system. If you power down your system prior to booting OpenBSD,
the card should be configured correctly.
SEE ALSOarp(4), cardbus(4), dcphy(4), ifmedia(4), intro(4), lxtphy(4),
netintro(4), nsphy(4), pci(4), hostname.if(5), ifconfig(8)
ADMtek AL981 and AL983 data sheets, http://www.admtek.com.tw.
ASIX Electronics AX88140A and AX88141 data sheets,
http://www.asix.com.tw.
Davicom DM9102 data sheet, http://www.davicom8.com.
Intel 21143 Hardware Reference Manual, http://developer.intel.com.
Macronix 98713/A, 98715/A and 98725 data sheets, http://www.macronix.com.
Macronix 98713/A and 98715/A app notes, http://www.macronix.com.
HISTORY
The dc device driver first appeared in FreeBSD 4.0. OpenBSD support was
added in OpenBSD 2.7.
AUTHORS
The dc driver was written by Bill Paul <wpaul@ee.columbia.edu> and ported
to OpenBSD by
Aaron Campbell <aaron@openbsd.org>.
BUGS
The Macronix application notes claim that in order to put the chips in
normal operation, the driver must write a certain magic number into the
CSR16 register. The numbers are documented in the app notes, but the ex-
act meaning of the bits is not.
The 98713A seems to have a problem with 10Mbps full duplex mode. The
transmitter works but the receiver tends to produce many unexplained er-
rors leading to very poor overall performance. The 98715A does not exhi-
bit this problem. All other modes on the 98713A seem to work correctly.
The original 82c168 PNIC chip has built-in NWAY support which is used on
certain early LinkSys LNE100TX and Matrox FastNIC cards, however it is
horribly broken and difficult to use reliably. Consequently, autonegotia-
tion is not currently supported for this chipset: the driver defaults the
NIC to 10baseT half duplex, and it's up to the operator to manually
select a different mode if necessary. (Later cards use an external MII
transceiver to implement NWAY autonegotiation and work correctly.)
The dc driver programs 82c168 and 82c169 PNIC chips to use the store and
forward setting for the transmit start threshold by default. This is to
work around problems with some NIC/PCI bus combinations where the PNIC
can transmit corrupt frames when operating at 100Mbps, probably due to
PCI DMA burst transfer errors.
The 82c168 and 82c169 PNIC chips also have a receiver bug that sometimes
manifests during periods of heavy receive and transmit activity, where
the chip will improperly DMA received frames to the host. The chips ap-
pear to upload several kilobytes of garbage data along with the received
frame data, dirtying several RX buffers instead of just the expected one.
The dc driver detects this condition and will salvage the frame, however
it incurs a serious performance penalty in the process.
The PNIC chips also sometimes generate a transmit underrun error when the
driver attempts to download the receiver filter setup frame, which can
result in the receive filter being incorrectly programmed. The dc driver
will watch for this condition and requeue the setup frame until it is
transferred successfully.
The ADMtek AL981 chip (and possibly the AN983 as well) has been observed
to sometimes wedge on transmit: this appears to happen when the driver
queues a sequence of frames which cause it to wrap from the end of the
transmit descriptor ring back to the beginning. The dc driver attempts to
avoid this condition by not queuing any frames past the end of the
transmit ring during a single invocation of the dc_start() routine. This
workaround has a negligible impact on transmit performance.
The mii_tick() function does not currently run for ASIX boards, meaning
cable disconnects and reconnects can go unnoticed. The AX88140A and
AX88141 data sheets indicate that they don't have RX or TX state regis-
ters (the bits are reserved). Therefore, we can't seem to reliably detect
when the adapter is idle.
The Davicom interfaces require a grossly high PCI latency timer value to
function properly. This means when a Davicom adapter is present in the
machine, it is given an unfairly high amount of bandwidth on the PCI bus,
unnecessarily taking time away from other devices. Therefore, Davicom
network cards are not recommended for use with OpenBSD. Be careful; some
motherboards have Davicom interfaces built-in.
MirOS BSD #10-current November 20, 1999 3
