Intel 21555 - Manual (Page 76)

76 21555 Non-Transparent PCI-to-PCI Bridge User Manual
Initialization Requirements
However, when the 21555 samples l_stat high once the INS_STAT bit is cleared, this indicates that the ejector
handle has been opened. This is interpreted as a removal event, and the 21555 enters the Signal Removal state
instead. The same is true when the 21555 samples l_stat high while in the Normal Operation state.
When the 21555 enters the Signal Removal state, the REM_STAT bit is set and p_enum_l is asserted to indicate
that a removal request is being made. Since the card is not yet ready for removal, the 21555 drives l_stat low in this
state to force the LED off. When desired, the LED can be turned on by setting the LOO bit. Clearing the LOO bit
causes the 21555 to drive l_stat low in this state.
After the software determines that the card is quiesced, or no longer performing or scheduling transactions, the host
clears the REM_STAT bit. the 21555 deasserts p_enum_l and stops driving l_stat low. When the LOO bit is set,
the 21555 continues to drive l_stat high. As long as the ejector handle stays open (l_stat sampled high), the LED
will be on, indicating that it is OK to remove the card. The 21555 is now in the Removal OK state.
When l_stat is sampled low either upon clearing of REM_STAT, or anytime during the Removal OK state, this
indicates that the ejector handle has been closed and the card is reseated. The 21555 enters the Signal Insertion
state, setting the INS_STAT bit and asserting p_enum_l. Since no local state has been lost, serial preload and
Primary Lockout Reset Value is not performed.