AM6442: UART DMA TX Callback Occurs Before UART is done

Part Number: AM6442

Tool/software:

Hello experts,

I am trying to communicate using UART DMA LLD but having a problem. Before starting a transaction, i am checking if tx_cb occured from the previous transaction, if it occured, then i start my transaction. But i believe tx_cb occures before UART actually finishes sending data. I believe this because the data byte count I sent and receive is different when my sending frequency is high, when I lower it though, receiver and transmitter has same data count. I checked the receiver with different transmitter and I dont have this problem.
Why do you think this might be happening?

Thanks for your helps,

Regards.