Display system and associated control method

1. A display system, is capable of connecting to a host, comprising:

a display controller;

a display port (DP), comprising a main link, an auxiliary channel, and a signal detection end;

a DP engine, coupled to the DP via the main link, the auxiliary channel and the signal detection end, for outputting an image signal to the display controller; and

a detection circuit, coupled to the DP via the auxiliary channel, for detecting whether a communication signal is present in an auxiliary signal pair in the auxiliary channel to output an indication signal to the DP engine, wherein the indication signal indicates whether the display controller is coupled to the host, and the indication signal is asserted to activate the DP engine when said communication signal is present in said auxiliary signal pair in said auxiliary channel.

2. The display system according to claim 1 , wherein the communication signal outputted from the auxiliary signal pair is a differential signal.

3. The display system according to claim 1 , wherein the communication signal sent from the DP is originated from the host.

4. The display system according to claim 1 , wherein the detection circuit comprises:

a first hysteresis comparator, having a positive input connected to a first end of the auxiliary signal pair, and a negative input connected to a second end of the auxiliary signal pair;

a second hysteresis comparator, having a positive input connected to the second end of the auxiliary signal pair, and a negative input connected to the first end of the auxiliary signal pair; and

an XOR gate, connected to an output of the first hysteresis comparator and an output of the second hysteresis comparator, having an output for outputting the indication signal.

5. The display system according to claim 4 , wherein the first hysteresis comparator and the second hysteresis comparator have a hysteresis voltage offset, which equals a first number minus a second number, with the first number being greater than the second number.

6. The display system according to claim 5 , wherein between the auxiliary signal pair is a signal difference; the indication signal of a second level is generated when the signal difference is decremental and is smaller than the second number;

and the indication signal of a first level is generated when the signal difference is incremental and is greater than the first number, and is for informing the DP engine to output the communication signal in the auxiliary signal pair.

7. A method for controlling a display system, the display system comprising a display controller, a first display port (DP) connected to a second DP of a host, and a DP engine for receiving the indication signal, the method comprising:

obtaining a signal difference of an auxiliary signal pair in an auxiliary channel of the first DP port;

generating an indication signal of a first level when the signal difference is incremental and is greater than a first number; and

generating the indication signal of a second level when the signal difference is decremental and is smaller than a second number

wherein, the first number is greater than the second number, and when the indication signal is the first level, it is determined that a communication signal is present in the auxiliary signal pair, and said indication signal is then sent to the DP engine for activating the DP engine to receive the communication signal and convert a signal in a main link of the DP port to an image signal to the display controller.

8. The method according to claim 7 , wherein the communication signal in the auxiliary signal pair is a differential signal.

9. The method according to claim 7 , wherein the communication signal outputted from the first DP port originates from the host.

10. The method according to claim 7 , wherein when the indication signal is the first level, the DP port is activated to receive the communication signal and convert a signal in a main link of the DP to an image signal to the display controller.

11. The method according to claim 10 , wherein the indication signal indicates whether the display controller is coupled to the host.