Details:

IEP timestamp can get corrupted if the nano second portion is zero. This issue is seen in 32-bit shadow mode and also seen with HW timestamp capture registers i.e. when IEPx_CAPR0_REG0(Nano seconds part is 0x00000) then IEPx_CAPR0_REG1 (milliseconds part) is retained as old value. Both RX_SOF(IEPx_CAPR0_REG0/1) capture register and TX_SOF(IEPx_CAPR4_REG0/1) capture register can be affected.

Examples:

• previous packet IEP0 timestamp at EOF: 0xE650(ms):0xf4084(ns)
• Next packet IEP0 timestamp from SOF IEP capture register: 0xE650(ms):0x00000(ns)
• Next packet IEP0 timestamp at l2 fifo drain check for 27 bytes: 0xE651(ms):0x1770(ns)

From the above, it is clear that IEP0 timestamp from capture register is incorrect because previous packet eof timestamp should be less than next packet sof timestamp.

Workaround(s):

If IEPx_CAPRx_REG0 (nano seconds part) from IEP capture register is 0x00000, then load the millisecond's part from IEPx_CAPRx_REG1.