System and method for transmitting USB data over a DisplayPort transmission link

Patent metadata

Field	Value
Publication number	US-9323698-B2
Application number	US-201113241127-A
Country	US
Kind code	B2
Filing date	Sep 22, 2011
Priority date	Sep 22, 2011
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

A data transmission system is provided. The data transmission system includes a source device having a source device controller and a register and a sink device having a sink device controller. The data transmission system also includes a transmission link coupling the source device and the sink device. The transmission link includes a unidirectional main line having a plurality of main link channels, a bidirectional auxiliary line configured to transmit data between the source device and the sink device at a first data rate, and a unidirectional interrupt line. The transmission link is configured to transmit data from the source device to the sink device over one of the main link lines at a second data rate and to transmit data from the sink device to the source device over the auxiliary line at the second data rate. The transmission link may comply with the DisplayPort standard, and the data may be transmitted in accordance with the USB standard.

First claim

What is claimed is:

1. A method of transmitting data between a source device coupled to a sink device comprising:
transmitting data from the source device to the sink device at a first standard data rate over a unidirectional main link comprising a plurality of main link lines;
receiving, while transmitting data from the source device to the sink device at the first standard data rate, data from the sink device at the source device at a second standard data rate over a bidirectional auxiliary line that is physically separate from the unidirectional main line, wherein the second standard data rate is slower than the first standard data rate;
receiving, at the source device, a first instruction to transmit data between the source device and the sink device at a modified data rate;
transmitting, after receiving the first instruction, data from the source device to the sink device at the modified data rate over a main link line of the plurality of main link lines, wherein the modified data rate is slower than the first standard data rate; and
receiving, after receiving the first instruction and while transmitting data to the sink device over the main link line, data from the sink device at the source device at the modified data rate over the bidirectional auxiliary line, wherein the modified data rate is faster than the second standard data rate.

2. The method of claim 1 , wherein the main link line comprises a portion of a DisplayPort connection, the bidirectional auxiliary line comprises a fast auxiliary line of the DisplayPort connection, and the first standard data rate and the second standard data rate are specified by a DisplayPort specification.

3. The method of claim 1 , wherein the modified data rate corresponds to a data rate associated with a Universal Serial Bus (USB) revision 3.0 standard.

4. The method of claim 1 , wherein the first instruction comprises a write to a DisplayPort Configuration Data (DPCD) register.

5. The method of claim 1 , further comprising:
receiving, at the source device, a second instruction to stop data transmission between the source device and the sink device.

6. The method of claim 5 , wherein the second instruction comprises a Hot Plug Detect (HPD) interrupt signal.

7. The method of claim 5 , further comprising:
while transmitting data from the source device to the sink device at the modified data rate over the main link line of the plurality of main link lines, and
while receiving data from the sink device at the source device at the modified data rate over the bidirectional auxiliary line,
transmitting, on other main link lines of the plurality of main link lines, audio and video data from the source device to the sink device at the first standard data rate.

8. A method for transmitting Universal Serial Bus (USB) data over a DisplayPort link coupling a sink device to a source device, comprising:
transmitting data from the source device to the sink device at a first DisplayPort standard data rate over a DisplayPort link comprising a plurality of main link lines and a bidirectional auxiliary line that is physically separate from the plurality of main link lines;
receiving, while transmitting data from the source device to the sink device at the first standard data rate, data from the sink device at the source device at a second DisplayPort standard data rate over the bidirectional auxiliary line, wherein the second DisplayPort standard data rate is slower than the first DisplayPort standard data rate;
receiving a first instruction at the source device to transmit the USB data over the DisplayPort link;
transmitting, after receiving the first instruction, the USB data over the bidirectional auxiliary line of the DisplayPort link from the source device to the sink device at a modified data rate, wherein the modified data rate is faster than the second DisplayPort standard data rate; and
receiving, after receiving the first instruction, the USB data over the bidirectional auxiliary line from the sink device at the source device at the modified data rate,
wherein the USB data transmission between the source device and the sink device comprises alternating half-duplex unidirectional transmission.

9. The method of claim 8 , wherein the modified data rate corresponds to a data rate associated with a USB revision 3.0 standard.

10. The method of claim 8 , wherein the first instruction comprises a write to a DisplayPort Configuration Data (DPCD) register.

11. The method of claim 8 , further comprising receiving, at the source device, a second instruction to stop transmission between the source device and the sink device at the modified data rate, wherein the second instruction comprises a Hot Plug Detect (HPD) interrupt signal.

12. A data transmission system, comprising:
a source device comprising a source device controller having a register populated with a first instruction;
a sink device comprising a sink device controller; and
a transmission link coupling the source device and the sink device, the transmission link comprising:
a unidirectional interrupt line;
a unidirectional main line comprising a plurality of main link lines and configured to transmit data at a first standard data rate before the register is populated with the first instruction;
a bidirectional auxiliary line that is physically separate from the unidirectional main line and configured to transmit data between the source device and the sink device at a second standard data rate before the register is populated with the first instruction, wherein the second standard data rate is slower than the first standard data rate, and
wherein the transmission link is configured by the source device controller, in response to population of the register with the first instruction, to transmit data from the source device to the sink device over one of the plurality of main link lines at a modified data rate and to transmit, while transmitting data from the source device to the sink device over one of the plurality of main link lines, data from the sink device to the source device over the bidirectional auxiliary line at the modified data rate; and
wherein the modified data rate is slower than the first standard data rate and faster than the second standard data rate.

13. The system of claim 12 , wherein the modified data rate corresponds to a data rate associated with a Universal Serial Bus revision 3.0 standard.

14. The system of claim 12 , wherein the data transmission system comprises a DisplayPort data transmission system.

15. The system of claim 14 , wherein audio/video data is transmitted between the source device and the sink device over the remaining main link lines while data is being transmitted from the source device to the sink device over the one of the plurality of main link lines at the modified data rate and while data is being transmitted from the sink device to the source device over the bidirectional auxiliary line at the modified data rate.

16. The system of claim 13 , wherein the transmission link is configured by the source device controller to stop transmission of data from the source device to the sink device at the modified data rate in response to a second instruction written in the register.

17. The system of claim 16 , wherein the second instruction comprises a Hot Plug Detect (HPD) interrupt signal.

18. The system of claim 12 , wherein the data transmission system is configured by the source device controller to only transmit data from the sink device to the source device at the modified data rate over the bidirectional aux

Assignees

• Park Ji
• Shamarao Prashant
• Synaptics Inc

Inventors

• Park Ji
• Shamarao Prashant

Classifications

• H04L69/08

  Protocols for interworking; Protocol conversion · CPC title

• G09G5/006 Primary

  Details of the interface to the display terminal (specific for a display terminal using a CRT G09G1/167; using a flat panel G09G3/2096; circuits for interfacing with colour displays G09G5/04) · CPC title

• G06F13/14 Primary

  Handling requests for interconnection or transfer · CPC title

• H04L12/4013

  Management of data rate on the bus (systems modifying transmission characteristics according to link quality H04L1/0001) · CPC title

• G09G2370/045

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