Driver Parameter Values and Definitions

The following sections describe the hme driver parameters, which are listed in Table 3-1.

Table 3-1 hme

Parameter	Status	Description
transceiver_inuse	Read only	Defines the current status
link_status	Read only	Defines the current status
link_speed	Read only	Defines the current status
link_mode	Read only	Defines the current status
ipg1	Read and write	Inter-packet gap parameter
ipg2	Read and write	Inter-packet gap parameter
use_int_xcvr	Read and write	Operational mode parameter
pace_size	Read and write	Operational mode parameter
adv_autoneg_cap	Read and write	Operational mode parameter
adv_100T4_cap	Read and write	Operational mode parameter
adv_100fdx_cap	Read and write	Operational mode parameter

Table 3-1 hme(Continued)

Parameter	Status	Description
adv_100hdx_cap	Read and write	Operational mode parameter
adv_10fdx_cap	Read and write	Operational mode parameter
adv_10hdx_cap	Read and write	Operational mode parameter
autoneg_cap	Read only	Local transceiver auto negotiation capability
100T4_cap	Read only	Local transceiver capability of the hardware
100fdx_cap	Read only	Local transceiver capability of the hardware
100hdx_cap	Read only	Local transceiver capability of the hardware
10fdx_cap	Read only	Local transceiver capability of the hardware
10hdx_cap	Read only	Local transceiver capability of the hardware
lp_autoneg_cap	Read only	Link partner auto negotiation capability
lp_100T4_cap	Read only	Link partner capability
lp_100fdx_cap	Read only	Link partner capability
lp_100hdx_cap	Read only	Link partner capability
lp_10fdx_cap	Read only	Link partner capability
lp_10hdx_cap	Read only	Link partner capability
instance	Read and write	Device instance
lance_mode	Read and write	Additional delay before transmitting a packet
ipg0	Read and write	Additional delay before transmitting a packet

Defining the Current Status

The read-only parameters described in Table 3-2 explain the operational mode of the interface. These parameters define the current status.

Table 3-2

Parameter	Values	Description
transceiver_inuse	0 1	= Internal transceiver = External transceiver
link_status	0 1	Current link status = Link down = Link up
link_speed	0 1	Valid only if the link is up = 10 Mbps = 100 Mbps
link_mode	0 1	Valid only if the link is up = Half duplex = Full duplex

Inter-Packet Gap Parameters

The Fast Ethernet Parallel Port SCSI (FEPS) ASIC supports programmable Inter-Packet Gap (IPG) parameters ipg1 and ipg2. The total IPG is the sum of ipg1 and ipg2. The total IPG is 9.6 microseconds when the link speed set by the auto-negotiation protocol is 10 Mbps. When the link speed is 100 Mbps, the total IPG is 0.96 microseconds.

Table 3-3 lists the default values and allowable values for the inter-packet gap (IPG) parameters, ipg1 and ipg2.

Table 3-3

Parameter	Values (Byte-time)	Description
ipg1	0, 255	ipg1 = 8 (default at initialization)
ipg2	0, 255	ipg2 = 4 (default at initialization)

By default, the driver sets ipg1 to 8-byte time and ipg2 to 4-byte time, which are the standard values. (Byte time is the time it takes to transmit one byte on the link, with a link speed of either 100 Mbps or 10 Mbps.)

If your network has systems that use longer IPG (the sum of ipg1 and ipg2) and if those machines seem to be slow in accessing the network, increase the values of ipg1 and ipg2 to match the longer IPGs of other machines.

Defining an Additional Delay Before Transmitting a Packet Using lance_mode and ipg0

The Fast Ethernet Parallel Port SCSI (FEPS) ASIC supports a programmable mode called lance_mode. The ipg0 parameter is associated with lance_mode.

After a packet is received with lance_mode enabled (default) an additional delay is added by setting the ipg0 parameter before transmitting the packet. This delay, set by the ipg0 parameter, is in addition to the delay set by the ipg1 and ipg2 parameters. The additional delay set by ipg0 helps to reduce collisions. Systems that have lance_mode enabled might not have enough time on the network.

If lance_mode is disabled, the value of ipg0 is ignored and no additional delay is set. Only the delays set by ipg1 and ipg2 are used. Disable lance_mode if other systems keep sending a large number of back-to-back packets.

You can set the additional delay with the ipg0 parameter from 0 to 31, which is the nibble time delay. Note that nibble time is the time it takes to transfer four bits on the link. If the link speed is 10 Mbps, nibble time is equal to 400 ns. If the link speed is 100 Mbps, nibble time is equal to 40 ns.

For example, if the link speed is 10 Mbps, and you set ipg0 to 20 nibble times, multiply 20 by 400 ns to get 800 ns. If the link speed is 100 Mbps, and you set ipg0 to 30 nibble-times, multiply 30 by 40 ns to get 120 ns.

Table 3-4 defines the lance_mode and ipg0 parameters.

Table 3-4 lance_modeipg0

Parameter	Values	Description
lance_mode	0 1	lance_mode disabled lance_mode enabled (default)
ipg0	1 0-31	Additional IPG before transmitting a packet (after receiving a packet)

1. The default value is 16 nibble-times, which is 6.4 microseconds for 10 Mbps and 0.64 microseconds for 100 Mbps.

Operational Mode Parameters

Table 3-5 describes the operational mode parameters and their default values.

Table 3-5

Parameter	Values	Description
adv_autoneg_cap	0 1	Local transceiver capability advertised by the hardware = Forced mode = Auto-negotiation (default)
1 adv_100T4_cap	0 1	Local transceiver capability advertised by the hardware; read/write parameter = Not 100BASE-T4 capable = 100BASE-T4 capable
1 adv_100fdx_cap	0 1	Local transceiver capability advertised by the hardware; read/write parameter = Not 100Mbit/sec full-duplex capable (default) = 100Mbit/sec full-duplex capable
1 adv_100hdx_cap	0 1	Local transceiver capability advertised by the hardware; read/write parameter = Not 100Mbit/sec half-duplex capable = 100Mbit/sec half-duplex capable (default)

Table 3-5 (Continued)

Parameter	Values	Description
1 adv_10fdx_cap	0 1	Local transceiver capability advertised by the hardware; read/write parameter = Not 10Mbit/sec full-duplex capable (default) = 10Mbit/sec full-duplex capable
1 adv_10hdx_cap	0 1	Local transceiver capability advertised by the hardware; read/write parameter = Not 10Mbit/sec half-duplex capable = 10Mbit/sec half-duplex capable (default)
use_int_xcvr	0 1	Local transceiver capability selected for networking by the user = External transceiver is used if connected (default) = Internal transceiver is used, even if the external transceiver is connected

1. The priority (in descending order) for these parameters is: adv_100T4_cap, adv_100fdx_cap, adv_100hdx_cap, adv_10fdx_cap, adv_10hdx_cap

Selecting the Internal or External Transceiver

Use the use_int_xcvr parameter to change the default behavior. For example, you can select the internal transceiver, even though the driver is capable of selecting the external transceiver. The driver, not the hardware, makes the selection between the internal and external transceiver.

If the external transceiver, which is connected to the MII interface, is present, the driver selects the external transceiver using the default use_int_xcvr 0. If the external transceiver is not present, the driver selects the internal transceiver. When this parameter is set to use_int_xcvr 1, the driver selects the internal transceiver, even if the external transceiver is connected.

Defining the Number of Back-to-Back Packets To Transmit

The pace_size parameter (see Table 3-6) defines the maximum number of back-to-back packets you can transmit at one time. If the value is zero, there is no limit to the number of back-to-back packets that can be transmitted.

Table 3-6

Parameter Values	Description
pace_size 1 to 255 0	= Number of back-to-back packets transmitted at one time = No limit to the number of back-to-back packets that can be transmitted (default)

Reporting Transceiver Capabilities

Table 3-7 describes the read-only transceiver capabilities (either the internal transceiver or the external transceiver), whichever is selected.

Table 3-7

Parameter	Values	Description
autoneg_cap	0 1	Local transceiver capability of the hardware = Not capable of auto-negotiation = Auto negotiation capable
100T4_cap	0 1	Local external transceiver capability of the hardware = Not 100BASE-T4 capable = 100BASE-T4 capable
100fdx_cap	0 1	Local transceiver capability of the hardware; initialized at startup = Not 100Mbit/sec full-duplex capable = 100Mbit/sec full-duplex capable

Table 3-7

Parameter	Values	Description
100hdx_cap	0 1	Local transceiver capability of the hardware; initialized at startup = Not 100Mbit/sec half-duplex capable = 100Mbit/sec half-duplex capable
10fdx_cap	0 1	Local transceiver capability of the hardware; initialized at startup = Not 10Mbit/sec full-duplex capable = 10Mbit/sec full-duplex capable
10hdx_cap	0 1	Local transceiver capability of the hardware; initialized at startup = Not 10Mbit/sec half-duplex capable = 10Mbit/sec half-duplex capable

The parameters in Table 3-7 define the capabilities of the hardware. The internal transceiver can support all of these capabilities. The capabilities of the external transceiver are dependent on the device. If the external transceiver is not capable of auto-negotiation but has the capability of all speeds and modes (100 Mbps, 10 Mbps, half-duplex, and full-duplex), you must determine the capabilities of the external transceiver.

Reporting the Link Partner Capabilities

Table 3-8 describes the read-only link partner capabilities.

Table 3-8

Parameter	Values	Description
lp_autoneg_cap	0 1	= No auto-negotiation = Auto-negotiation
lp_100T4_cap	0 1	= No 100BASE-T4 = 100BASE-T4
lp_100fdx_cap	0 1	= No100Mbit/sec full-duplex transmission = 100Mbit/sec full-duplex

Table 3-8 (Continued)

Parameter	Values	Description
lp_100hdx_cap	0 1	= No 100Mbit/sec half-duplex transmission = 100Mbit/sec half-duplex
lp_10fdx_cap	0 1	= No 10Mbit/sec full-duplex transmission = 10Mbit/sec full-duplex
lp_10hdx_cap	0 1	= No 10Mbit/sec half-duplex transmission = 10Mbit/sec half-duplex

If the link partner is not capable of auto-negotiation (when lp_autoneg_cap is 0) the information described in Table 3-8 is not relevant and the parameter value=0.

If the link partner is capable of auto-negotation (when lp_autoneg_cap is 1) then the speed and mode information is displayed when you use auto-negotiation and get the link partner capabilities.