man/man4/dc.4

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.\"	Bill Paul <wpaul@ee.columbia.edu>. All rights reserved.
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.\" $FreeBSD$
.\"
.Dd November 20, 1999
.Dt DC 4 i386
.Os FreeBSD
.Sh NAME
.Nm dc
.Nd
DEC/Intel 21143 and clone 10/100 ethernet driver
.Sh SYNOPSIS
.Cd "device miibus"
.Cd "device dc"
.Sh DESCRIPTION
The
.Nm
driver provides support for several PCI fast ethernet adapters and
embedded controllers based on the following chipsets:
.Pp
.Bl -bullet -compact -offset indent
.It
DEC/Intel 21143
.It
Macronix 98713, 98713A, 98715, 98715A, 98725, 98727 and 98732
.It
Davicom DM9100, DM9102 and DM9102A
.It
ASIX Electronics AX88140A and AX88141
.It
ADMtek AL981 Comet and AN985 Centaur
.It
Lite-On 82c168 and 82c169 PNIC
.It
Lite-On/Macronix 82c115 PNIC II
.El
.Pp
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
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.
.Pp
Some clone chips duplicate the 21143 fairly closely while others
only maintain superficial simularities.
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
.Nm
driver does its best to provide generalized support for all
of these chipsets in order to keep special case code to a minimun.
.Pp
These chips are used by many vendors which makes it
difficult provide a complete list of all supported cards.
The
following NICs are known to work with the
.Nm
driver at this time:
.Pp
.Bl -bullet -compact -offset indent
.It
Digital DE500-BA 10/100 (21143, non-MII)
.It
Built in DE500-BA on DEC Alpha workstations (21143, non-MII)
.It
Built in 10Mbps only ethernet on Compaq Presario 7900 series
desktops (21143, non-MII)
.It
Built in ethernet on LinkSys EtherFast 10/100 Instant GigaDrive (DM9102, MII)
.It
Kingston KNE100TX (21143, MII)
.It
D-Link DFE-570TX (21143, MII, quad port)
.It
NDC SOHOware SFA110A (98713A)
.It
NDC SOHOware SFA110A Rev B4 (98715AEC-C)
.It
SVEC PN102-TX (98713)
.It
CNet Pro120A (98715A or 98713A) and CNet Pro120B (98715)
.It
Compex RL100-TX (98713 or 98713A)
.It
LinkSys LNE100TX (PNIC 82c168, 82c169)
.It
NetGear FA310-TX Rev. D1, D2 or D3 (PNIC 82c169)
.It
Matrox FastNIC 10/100 (PNIC 82c168, 82c169)
.It
Kingston KNE110TX (PNIC 82c169)
.It
LinkSys LNE100TX v2.0 (PNIC II 82c115)
.It
Jaton XpressNet (Davicom DM9102)
.It
Alfa Inc GFC2204 (ASIX AX88140A)
.It
CNet Pro110B (ASIX AX88140A)
.El
.Pp
The
.Nm
driver supports the following media types:
.Pp
.Bl -tag -width xxxxxxxxxxxxxxxxxxxx
.It autoselect
Enable autoselection of the media type and options.
The user can manually override
the autoselected mode by adding media options to the
.Pa /etc/rc.conf
file.
.Pp
Note: the built-in NWAY autonegotiation on the original PNIC 82c168
chip is horribly broken and is not supported by the
.Nm
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.
.It 10baseT/UTP
Set 10Mbps operation.
The
.Ar mediaopt
option can also be used to enable
.Ar full-duplex
operation.
Not specifying
.Ar full duplex
implies
.Ar half-duplex
mode.
.It 100baseTX
Set 100Mbps (fast ethernet) operation.
The
.Ar mediaopt
option can also be used to enable
.Ar full-duplex
operation.
Not specifying
.Ar full duplex
implies
.Ar half-duplex
mode.
.El
.Pp
The
.Nm
driver supports the following media options:
.Pp
.Bl -tag -width xxxxxxxxxxxxxxxxxxxx
.It full-duplex
Force full duplex operation.
The interface will operate in
half duplex mode if this media option is not specified.
.El
.Pp
Note that the 100baseTX media type may not be available on certain
Intel 21143 adapters which support 10mbps media attachments only.
For more information on configuring this device, see
.Xr ifconfig 8 .
.Sh DIAGNOSTICS
.Bl -diag
.It "dc%d: couldn't map ports/memory"
A fatal initialization error has occurred.
.It "dc%d: couldn't map interrupt"
A fatal initialization error has occurred.
.It "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, of if there is a problem with
the network connection (cable).
.It "dc%d: no memory for rx list"
The driver failed to allocate an mbuf for the receiver ring.
.It "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.
.It "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
transfered into its FIFO memory.
.It "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.
.Pp
Note that this condition only occurs when warm booting from another
operating system.
If you power down your system prior to booting
.Fx ,
the card should be configured correctly.
.El
.Sh SEE ALSO
.Xr arp 4 ,
.Xr netintro 4 ,
.Xr ng_ether 4 ,
.Xr ifconfig 8
.Rs
.%T ADMtek AL981, AL983 and AL985 data sheets
.%O http://www.admtek.com.tw
.Re
.Rs
.%T ASIX Electronics AX88140A and AX88141 data sheets
.%O http://www.asix.com.tw
.Re
.Rs
.%T Davicom DM9102 data sheet
.%O http://www.davicom8.com
.Re
.Rs
.%T Intel 21143 Hardware Reference Manual
.%O http://developer.intel.com
.Re
.Rs
.%T Macronix 98713/A, 98715/A and 98725 data sheets
.%O http://www.macronix.com
.Re
.Rs
.%T Macronix 98713/A and 98715/A app notes
.%O http://www.macronix.com
.Re
.Sh HISTORY
The
.Nm
device driver first appeared in
.Fx 4.0 .
.Sh AUTHORS
The
.Nm
driver was written by
.An Bill Paul Aq wpaul@ee.columbia.edu .
.Sh 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 exact meaning of the bits is not.
.Pp
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.
.Pp
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.)
.Pp
The
.Nm
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.
.Pp
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
.Nm
driver detects this condition and will salvage the frame, however
it incurs a serious performance penalty in the process.
.Pp
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
.Nm
driver will watch for this condition and requeue the setup frame until
it is transfered successfully.
.Pp
The ADMtek AL981 chip (and possibly the AN985 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
the transmit descriptor ring back to the beginning.
The
.Nm
driver attempts to avoid this condition by not queing any frames past
the end of the transmit ring during a single invocation of the
.Fn dc_start
routine.
This workaround has a negligible impact on transmit performance.