A system that includes a host and a peripheral device. The host transmits a packet that includes a command and a flow control field. The peripheral device receives the packet and has the ability to execute the command, wherein the peripheral device can determine whether the command can be processed in a timely manner, and can update the packet's flow control field with flow control data based on the determination. The host receives the updated packet and has the ability to adjust the flow control of subsequent packets to the peripheral device based on the flow control data in the updated packet.