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Intel 8255x 10/100 Mbps Ethernet Controller Family Open Source Software Developer Manual 21
PCI Interface
4.1.18.5 Ethernet Power Consumption Registers (Offset E2h)
The Data Register is an 8-bit read-only register providing a mechanism for the device to report
state dependent maximum power consumption and heat dissipation. The value reported in this
register depends on the value written to the Data Select field in the PMCSR register.
The power measurements defined in the register have a dynamic range of 0 to 2.55 W with 0.01 W
resolution according to the data scale.
Note: The required accuracy should be in the range of +20% and -10%. The 82557 and 82558 do not
implement this register. The 82559 and later Intel Fast Ethernet controllers do. The value reported
in this register is hard-coded in the 82559 silicon. The structure of the data register is presented
below:
NOTE: The D1 and D2 power states are not currently supported by operating systems.
4.2 PCI Command Usage
The table below lists the PCI commands that the various Intel Fast Ethernet controllers can use.
Table 6. Power Consumption / Dissipation Reporting
Data Select Data Scale Data Reported
0 2 D0 Power Consumption = 58 (580 mW)
1 2 D1 Power Consumption = 40 (400 mW)
2 2 D2 Power Consumption = 40 (400 mW)
3 2 D3 Power Consumption = 40 (400 mW)
4 2 D0 Power Dissipated = 58 (580 mW)
5 2 D1 Power Dissipated = 40 (400 mW)
6 2 D2 Power Dissipated = 40 (400 mW)
7 2 D3 Power Dissipated = 40 (400 mW)
8 2 Common Function Power Dissipated = 00
9-15 0 Reserved 00 h