Sharing a graphics-processing-unit display port

Patent metadata

Field	Value
Publication number	US-9477437-B2
Application number	US-201514746623-A
Country	US
Kind code	B2
Filing date	Jun 22, 2015
Priority date	Oct 2, 2012
Publication date	Oct 25, 2016
Grant date	Oct 25, 2016

Abstract

An electronic device selectively couples a head with links in a graphics processing unit to a currently selected display port in a pair of display ports. During operation, control logic in the electronic device monitors a pair of configuration signals from the pair of display ports, where the pair of configuration signals correspond to physical connections to the pair of display ports. Then, the control logic determines a selection control signal based on the monitored pair of configuration signals, a policy setting and a default display port, where the selection control signal specifies the currently selected display port. Moreover, the control logic provides the selection control signal to a multiplexer in the electronic device. Next, the multiplexer selectively couples the head with the links in the graphics processing unit to the currently selected display port based on the selection control signal.

First claim

What is claimed is:

1. An electronic-device, comprising:
a graphics processing unit comprising a head, the head comprising links configured to communicate video signals, audio signals, data signals and a first configuration signal corresponding to a physical connection to a currently selected display port in a pair of display ports;
a multiplexer electrically coupled to the graphics processing unit, control logic and the pair of display ports, the multiplexer configured to selectively couple the links in the head to the currently selected display port based on a selection control signal that specifies the currently selected display port;
the control logic, electrically coupled to the pair of display ports and the multiplexer, configured to monitor a pair of configuration signals and to provide the selection control signal to the multiplexer based on the monitored pair of configuration signals, a policy setting and a default display port, the control logic being further configured to provide an enable signal to the multiplexer; and
wherein, based on the enable signal, the multiplexer is further configured to break the selective coupling to the previously selected display port before making the selective coupling to the currently selected display port.

2. The electronic device of claim 1 , wherein the enable signal comprises a programmable duration.

3. The electronic device of claim 1 , wherein, the multiplexer is configured to decouple the graphics processing unit from the pair of display ports for a time duration when the selective coupling has changed, and wherein the electronic device further comprises a processor and a non-transitory computer-readable medium comprising one or more instructions which when executed by the processor detects a change in the first configuration signal.

4. The electronic device of claim 1 , wherein the multiplexer includes an analog multiplexer.

5. The electronic device of claim 1 , wherein the pair of configuration signals includes hot-plug detect signals associated with the pair of display ports; and
wherein a given hot-plug detect signal is asserted when a display is physically connected to a given one of the pair of display ports.

6. The electronic device of claim 1 , wherein the control logic includes a filter configured to filter transient signals in the pair of configuration signals.

7. The electronic device of claim 1 , wherein the policy setting includes one of: first-come, first-serve servicing, and priority-based servicing.

8. The electronic device of claim 1 , wherein the default display port includes one of the pair of display ports.

9. The electronic device of claim 1 , wherein the electronic device is configured to selectively couple the links in the head to the currently selected display port without using a software driver.

10. The electronic device of claim 1 , wherein the control logic is configured to determine the selection control signal using combinatorial logic.

11. The electronic device of claim 1 , wherein the control logic is other than a processor.

12. The electronic device of claim 1 , wherein the pair of display ports include physical connectors; and
wherein a given display port only includes a predefined number of pins associated with a particular audio/video interface format.

13. The electronic device of claim 1 , wherein the policy setting and the default display port are specified by a hardware component electrically coupled to the control logic.

14. The electronic device of claim 1 , further comprising a processor and a non-transitory computer readable medium comprising one or more instructions which when executed by the processor specify the policy setting and the default display port.

15. A system, comprising:
a graphics processing unit having a head with links configured to communicate video signals, audio signals, data signals and a first configuration signal corresponding to a physical connection to a currently selected display port in a pair of display ports;
a multiplexer electrically coupled to the graphics processing unit, control logic and the pair of display ports, configured to selectively couple the links in the head to the currently selected display port based on a selection control signal that specifies the currently selected display port;
the pair of display ports, electrically coupled to the multiplexer and the control logic, configured to couple to displays and to communicate the video signals, the audio signals and a pair of configuration signals corresponding to the pair of display ports, wherein the pair of configuration signals includes the first configuration signal;
the control logic, electrically coupled to the pair of display ports and the multiplexer, configured to monitor the pair of configuration signals and to provide the selection control signal to the multiplexer based on the monitored pair of configuration signals, a policy setting and a default display port;
wherein the multiplexer is configured to decouple the graphics processing unit from the pair of display ports for a time duration when the selective coupling has changed; and
a processor and a non-transitory computer-readable medium comprising one or more instructions which when executed by the processor detects a change in the configuration signal characterized by the time duration.

16. The system of claim 15 , wherein the control logic is further configured to provide an enable signal to the multiplexer; and
wherein, based on the enable signal, the multiplexer is configured to break a first selective coupling to the previously selected display port before a second selective coupling to the currently selected display port is made.

17. The system of claim 15 , wherein a hardware component electrically coupled to the control logic is configured to specify the policy setting and the default display port.

18. An electronic device-implemented method for selectively coupling a head with links in a graphics processing unit in an electronic device to a currently selected display port in a pair of display ports, wherein the method comprises:
using control logic in the electronic device, monitoring a pair of configuration signals from the pair of display ports, wherein the pair of configuration signals correspond to physical connections to the pair of display ports;
using the control logic, determining a selection control signal based on the monitored pair of configuration signals, a policy setting and a default display port, wherein the selection control signal specifies the currently selected display port;
providing the selection control signal to a multiplexer in the electronic device; and
selectively coupling the head with the links in the graphics processing unit to the currently selected display port based on the selection control signal; and
when changing the selective coupling, decoupling the graphics processing unit from the pair of display ports for a time duration so that software executing on the electronic device detects a change in at least one of the pair of configuration signals.

19. The method of claim 18 , wherein the pair of configuration signals include hot-plug detect signals associated with the pair of display ports; and
wherein a given hot-plug detect signal is asserted when a display is physically connected to a given one of the pair of display ports.

20. The method of claim 18 , wherein the act of selectively coupling the head with the links to the currently selected display port is compatible with different operating systems that ca

Assignees

• Apple Inc

Inventors

• Ferry William O
• Redman David J
• Sheppard Adrian T
• Anantharaman Sreeraman

Classifications

• G09G2370/045

  using multiple communication channels, e.g. parallel and serial · CPC title

• G09G2370/042

  for monitor identification · CPC title

• G06F13/385

  for adaptation of a particular data processing system to different peripheral devices · CPC title

• G09G2360/02

  Graphics controller able to handle multiple formats, e.g. input or output formats · CPC title

• G09G2370/12

  Use of DVI or HDMI protocol in interfaces along the display data pipeline · CPC title