AXI5: AtomicCompare transactions.

Hi all,

After reading the AXI5 specification, I ran into some doubts regarding the AWLEN of AtomicCompare transactions. As per the specification, we can have AWLEN > 0 which ultimately means we can have multiple beats for a particular transaction and for AtomicCompare type of transaction with aligned address and AWBURST as INCR, how should I transmit the WDATA?

Here is a scenario:

BUS_WIDTH = 32bits
AWSIZE = 2 (4 Bytes)
AWLEN = 3 (4 Beats)
AWBURST = INCR
AWATOP = AtomicCompare
AWADDR = 0x00

What will be the WDATA?

Here C = 1 Byte Compare Data and S = 1 Byte Swap Data.

Case 1:

WDATA[0] = CCCC
WDATA[1] = SSSS
WDATA[2] = CCCC
WDATA[3] = SSSS

Case 2:

WDATA[0] = CCCC
WDATA[1] = CCCC
WDATA[2] = SSSS
WDATA[3] = SSSS

Thanks,

Raghav Rastogi.