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strange issue in marvell 88e1111 - loopback configuration

Honored Contributor II



i am using a phy (marvell 88e1111) connected via a rgmii port. this is a quadphy (marvell 88e1145) having 4 marvell 88e1111 phys in it for my 4 rgmii ports.  


that is, 4 rgmii ports, each connected to a 88e1111 phy. in all the four ports i have configured the autonegotiation and the value of control register is 1140 after restarting the phy.  


now the problem is as below.  


one of the rgmii port (let say port 0), i connect the cable to the outer network. because of which the link becomes active. for the other 3 ports (let say port 1, 2 and 3) there is no cable connected.  

after this i try to configure the rgmii port 0's PHY in loopback mode (by setting the loopback bit in Control register as 1). then i send the packet onto the rgmii port 0. the packet is neither received on the network nor it is looped back.  


but if i try the same loopback configuration on rgmii ports 1, 2 or 3 (all these ports have not be connected to physical wire and hence the link is not active), the packets are looped back correctly.  


is it possible to set the PHY in loopback mode after the link status is up?  


kindly help me to fix this issue.
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Honored Contributor II

can you please answer this simple question Marvel Alaska 88e1111 is software programmable? or hardware programmable only by changing low high states on its pin?

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