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DC(4)

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NAME    [Toc]    [Back]

     dc - DEC/Intel 21140, 21142, 21143, 21145 and clones  10/100
Ethernet

SYNOPSIS    [Toc]    [Back]

     dc* at pci? dev ? function ?
     dc* at cardbus? dev ? function ?
     dcphy* at mii? phy ?
     nsphy* at mii? phy ?
     lxtphy* at mii? phy ?

DESCRIPTION    [Toc]    [Back]

     The dc driver provides support for several PCI, MiniPCI, and
CardBus Fast
     Ethernet adapters and embedded controllers based on the following
     chipsets:

           +o   DEC 21140 PCI
           +o   DEC/Intel 21143 PCI and CardBus
           +o   Intel 21145 PCI
           +o    Macronix  98713,  98713A,  98715,  98715A, 98725,
98727, and 98732
           +o   Davicom DM9100, DM9102, and DM9102A
           +o   ASIX Electronics AX88140A and AX88141
           +o   ADMtek AL981 Comet PCI and AN983 Centaur-P PCI
           +o   ADMtek AN985 Centaur-C CardBus
           +o   Lite-On 82c168 and 82c169 PNIC
           +o   Lite-On/Macronix 82c115 PNIC II
           +o   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 duplex,
  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 attachments.
   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 order
 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:

           +o   Digital DE500-BA 10/100 (21143, non-MII)
           +o    Built-in  DE500-BA  on  DEC  Alpha   workstations
(21143, non-MII)
           +o    Built-in Ethernet on LinkSys EtherFast 10/100 Instant GigaDrive
               (DM9102, MII)
           +o   Kingston KNE100TX (21143, MII)
           +o   D-Link DFE-570TX (21143, MII, quad port)
           +o   NDC SOHOware SFA110A (98713A)
           +o   NDC SOHOware SFA110A Rev B4 (98715AEC-C)
           +o   SVEC PN102-TX (98713)
           +o   CNet Pro120A (98715A or 98713A) and  CNet  Pro120B
(98715)
           +o   Compex RL100-TX (98713 or 98713A)
           +o   LinkSys LNE100TX (PNIC 82c168, 82c169)
           +o   NetGear FA310-TX Rev. D1, D2 or D3 (PNIC 82c169)
           +o   Matrox FastNIC 10/100 (PNIC 82c168, 82c169)
           +o   Kingston KNE110TX (PNIC 82c169)
           +o   LinkSys LNE100TX v2.0 (PNIC II 82c115)
           +o   Jaton XpressNet (Davicom DM9102)
           +o   Alfa Inc GFC2204 (ASIX AX88140A)
           +o   CNet Pro110B (ASIX AX88140A)
           +o   LinkSys LNE100TX v4.x (ADMtek AN983 Centaur-P)
           +o    Xircom CardBus, including RealPort models (Xircom
X3201)
           +o   IBM EtherJet 10/100 CardBus (Intel 21143)
           +o   Accton EN1217 (98715) and EN2242 (ADMtek Centaur)
           +o   Mototech ME316 (ADMtek Centaur)
           +o   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
                  original 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 specifying
 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 configuring
 this device, see ifconfig(8).

DIAGNOSTICS    [Toc]    [Back]

     dc%d: couldn't map ports/memory  A fatal initialization  error has occurred.


     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 ALSO    [Toc]    [Back]

      
      
     arp(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.in-
tel.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    [Toc]    [Back]

     The dc device driver first appeared in FreeBSD 4.0.  OpenBSD
support was
     added in OpenBSD 2.7.

AUTHORS    [Toc]    [Back]

     The    dc    driver    was    written    by    Bill     Paul
<wpaul@ee.columbia.edu> and ported
     to OpenBSD by
     Aaron Campbell <aaron@openbsd.org>.

BUGS    [Toc]    [Back]

     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 exact
 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 errors
 leading to very poor overall performance.   The  98715A
does not exhibit
  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, autonegotiation
 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 appear
 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 registers
  (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.

OpenBSD      3.6                        November     20,     1999
[ Back ]
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