TC9205M
Preliminary Data Sheet
9
Physical Layer Configuration / Polling
TC9205M embeds a Physical Layer MII Management configuration / polling entity which provides speed,
duplex, link status and link partner full duplex flow control ability information to the switch. This
information is obtained by continuously polling the status of Physical Layer devices through the serial
management interface. The entity is under control of EEPROM settings and it can operate in four
different modes. The polling entity also performs Phy configuration procedure at two seconds after reset
and each time EEPROM control information changes.
The following operating modes are available per port basis (selectable by ANMode field from EEPROM's
ConfigRegP[x]):
00 – Normal Mode (assumed by default when EEPROM is not present):In
this
mode
the
Auto-Negotiation Enable bit from MII Control Register (0.12) is checked first. If it is found enabled then
TC9205M will disable advertisement for 1000BASE-T half duplex technology (9.8) and will advertise
the full duplex flow control ability (4.10:11) according with internal flow control enable settings.
Auto-negotiation is restarted leaving unchanged the rest of technology advertisements. Then
Auto-Negotiation Advertisement register (4), Link Partner Base Page Ability register (5) and GMII
registers (9:10) are polled continuously at 2 seconds interval in order to execute highest common
denominator resolution. If auto-negotiation is disabled as reported by 0.12 then the switch will configure
itself using bits 0.13 and 0.8 of Control register, and will consider link partner full duplex flow control
capable. Gigabit speed will be disabled.
01 – Advertise one mode:
Auto-Negotiation Enable is checked and if found to be disabled
TC9205M will attempt to enable it. If successful the switch will force the port’s speed and duplex mode
by advertising only the technology corresponding to the Speed and Duplex fields from EEPROM's
ConfigRegP[x], otherwise bits 0.8 and 0.13 will be read for configuration and gigabit speed will be
disabled. Full duplex flow control ability is also advertised along with selected technology and then
auto-negotiation is restarted. An auto-negotiation register polling is executed as in Normal Mode.
10 – Advertise multiple modes:
This mode is similar with previous one except that it advertises
the technology corresponding to the forced mode and all lower position technologies, down to
10BASE-T half duplex.
11 – Disable Auto-Negotiation: When this mode is selected then auto-negotiation is disabled by
setting bit 0.12 to ‘0’ and the forced speed and duplex mode will be written to Configuration Register,
bits 0.13, 0.6 and 0.8. This mode is available only for 10/100 Mbps speed modes so bit 0.6 will always
be written as ‘0’. Link partner will be considered full duplex flow control capable.
In addition to the force mode feature, the TC9205M internal speed and duplex can be chosen between
enforced ones (Speed and Duplex fields from EEPROM's ConfigRegP[x]) and polling results by means
of ForceIntMode configuration.
Independently of Phy configuration/polling operation mode the Link Status is also permanently monitored.
If a Physical device reports link failure via 1.2 status bit then TC9205M disables transmission on
associated port without holding any memory resources allocated for its transmission queues. The
reported Link Status can be forced to ‘1’ using ForceLink bit from the same ConfigRegP[x] register.
Confidential.
23/51
July 30, 2003
Copyright © 2003, IC Plus Corp.
TC9205M-DS-R03
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