Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
Target Requested Retries
Target Aborts
When the S5935 FIFO registers are accessed (S5935
as a target) and data is unavailable (empty FIFO) for
read transfers or cannot be accepted for write trans-
fers (full FIFO), the S5935 immediately terminates the
cycle by requesting a retry. The S5935 also initiates a
retry for Pass-Thru writes where the Add-On has not
completed the preceding Pass-Thru write by asserting
PTRDY#, and for Pass-Thru reads where the Add-On
cannot supply data within 8 PCI clocks (16 clocks for
the first data phase of a burst). A retry is requested by
a target asserting both STOP# and DEVSEL# while
TRDY# is deasserted. Figure 11 shows the behavior of
the S5935 when performing a target-initiated retry.
A target abort termination represents an error condi-
tion where no number of retries will produce a
successful target access. A target abort is uniquely
identified by the target deasserting DEVSEL# and
TRDY# while STOP# is asserted. When a target per-
forms an abort, it must also set bit 11 of its PCI Status
register. The S5935 configuration and operation regis-
ters never respond with a target abort when accessed.
If the S5935 encounters this condition when operating
as a PCI initiator, the S5935 sets bit 12 (received tar-
get abort) in the PCI Status register. Figure 12 depicts
a target abort cycle.
Target termination types are summarized in Table 2.
Figure 56. Target-Initiated Retry
3
2
1
45
PCI CLOCK
FRAME #
IRDY#
(I)
(I)
(T)
(T)
TRDY#
STOP#
(T)
DEVSEL#
INITIATOR
SEQUENCES IRDY#
+ FRAME# TO RETURN
TARGET
RETRY
TO IDLE STATE
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
SIGNALED
Table 42. Target Termination Types
Termination DEVSEL# STOP# TRDY#
Comment
Disconnect
Retry
on
on
off
on
on
on
on
off
off
Data is transferred. Transaction needs to be reinitiated to complete.
Data was not transferred. Transaction should be tried later.
Data was not transferred. Fatal error.
Abort
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