"WARNING: TX SGDMA TImeout" and no data sent

When an Ethernet packet is to be transmitted, the TSE driver places it into the SGDMA buffer and requires the transfer; then it polls the dma status register for completion.

The timeout error means that the dma status is still busy after a time, namely the data can't be transferred to the TSE.

This could be due to a some problem in DMA or TSE module. Did you check if timing is met?

Initialization and autonegotiation can complete regularly, because dma is not involved as long as you don't send or receive packets.