ALtera TSE frame reception

I am working with Altera TSE for data communication over ethernet. I am sending raw ethernet frames using tse_mac_raw_send() api & on h/w I can see TX led blinking, now for reception I am getting data in tse_sgdmaRx_isr(),here the data is stored in 2048 size rxsgdma_data[2048], so how can I get the exact length of ethernet frame received? Is there any other API for reception & I can not see RX led blinking if it is showing some data received in rxsgdma_data[] buffer.