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DRA756: the sent data not valid with PHY-less connection

Part Number: DRA756
Other Parts Discussed in Thread: DP83TC811EVM

Hi there,

# Hardware connection

There is a DRA756 customed board. Its ethernet connection is shown below.

- DRA7 is connected to Marvell Switch 88EA6321 port 2 through RGMII, which is set with Linux fixed-link {100Mbps, full-duplex}

- MCU connects to port 5 through RMII. MCU powers on at frist and configure switch and phy (Marvell 88Q2112) through SMI clause 22. Then MCU powers on DRA7

- Marvell PHY 88Q2112 connects to port 6, on the other side of which is connected to a PC with DP83TC811EVM

- This local network is not connect to external network.

- MCU is running bare-metal code without IP stack

# Problem details and background

- "the sent data" is from DRA7 chip with command below. PC ip (169.254.102.129) is determined by DP83TC811EVM

ifconfig eth0 169.254.102.120 netmask 255.255.255.0
ping 169.254.102.129

- iodelay recalibration part in DRA7 is bypass. Because the recalibration function returns error. More details can be found here[1]

- port 5 and port 6 data communication is verified, which means both side can send and receive the other side data.

- port 2 and port 6 are configured in the same way, which is forced speed with 100Mbps and forced link

- "not valid" means that data from DRA7 into port 2 cannot egress from any other port. But port 2 is able to receive data from other ports

- Even if VLAN table bit is set, the sent data from DRA7 into port 2 hope to send to DRA7 by port 2 again. However, there is no data shown for port 2 egress pin

- The way I confrim whether there is port ingress or egress data is probing for waveform on 88EA6321 pins 

- Below is some waveform screen capture of emac[0].txd[0:3] & txctl also port2.rxd[0:3] & rxctl

figure 1 switch port2 rxctl (yellow) rxd0 (green)

figure 2 switch port2 rxctl (yellow) rxd1 (green)


figure 3 switch port2 rxctl (yellow) rxd2 (green)


figure 4 switch port2 rxctl (yellow) rxd3 (green)


# Question

I am doubt about why the data sent from DRA7 cannot be captured by switch. And hope someone share insights with me. Thanks very much !

# Reference

[1] e2e.ti.com/.../906069