Patent Application
20130335430
1. Field of the Invention
The present invention relates in general to the field of information handling system display device communication, and more particularly to a configurable information handling system display communication link.
2. Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Often, information handling systems process information with the goal of presenting results of the processing at a display for an end user. Displays typically use a large number of pixels, each of which presents a color so that the totality of pixels presents an image. For example, a high definition display has a native resolution of at least 1920×1080 pixels. Generally, once an information handling system has generated information for presentation at a display, a graphics processor of the information handling system creates pixel values from the information that create the visual image at the display. The graphics system communicates the pixel values to a timing controller, which sets the pixel values to present the image with each pixel having a color defined by its pixel value. Static images, such as word processing documents, do not change pixel values very often so that the same values are repeatedly refreshed at the display. Dynamic images, such as movies, can change pixel values quite rapidly as images move on the display. In order to show moving images with clarity, large amounts of data can be sent from an information handling system to a display. In order to accommodate communication of pixel values to a display, the industry has developed a variety of standards for sending pixel values as digital information, including the DVI, HDMI and DisplayPort standards.
The DisplayPort standard defines a cable and interface that communicate pixel values from a graphics system to a display on four unidirectional data serial links and also includes a bi-directional auxiliary link that communicates management information between the graphics system and display. For example, the auxiliary link allows the display to provide an identifier to the graphics system for automated setup. The DisplayPort standard calls for a relatively low bandwidth across the auxiliary link, however, one alternative to the standard auxiliary link that provides increased bandwidth on the auxiliary link is to use a USB link as the auxiliary link. Having additional bandwidth allows communication of additional information between the display and graphics system, such as information associated with peripherals coupled to the display. For example, a mouse, video camera, memory card reader or speakers can interface with a port or wireless transceiver at the display and then use the USB auxiliary link to communicate with the information handling system through a DisplayPort cable. The extra bandwidth provided by the USB serial link reduces the number of separate cables that are needed to interface the display with its peripherals. If even more bandwidth is needed, one alternative approach is to support bi-directional communication with the unidirectional data serial links that normally communicate pixel values. DisplayPort can generally support the resolution of high definition displays with just two unidirectional data serial links so that the two remaining data serial links can be “borrowed” to support communication of other data, such as with the PCIe or USB protocols. However, “borrowing” two data serial links to establish one PCIe link provides a limited solution that may not efficiently use available bandwidth. As display resolution increases, “borrowing” display data links to create a PCIe link will impact the presentation of images at the display due to restricted bandwidth through the two data links.
Therefore a need has arisen for a system and method which supports presentation of information at a display through a cable that selectively includes non-pixel data.
In accordance with the present invention, a system and method are provided which substantially reduce the disadvantages and problems associated with previous methods and systems for communicating information between a display and an information handling system. A protocol selection controller adapts the protocol used on each of plural data links of a display cable to communicate peripheral and display information between a display and an information handling system through the display cable. The data links of the display cable can adapt to communicate peripheral information and display information with the peripheral information communicated in a selected of plural protocols.
More specifically, an information handling system has plural components disposed in a housing that cooperate to generate information for presentation of images at a display. A graphics system processes the information to generate pixel values that define the image at the display and provide the pixel values at a graphics connector for communication to a display, such as a DisplayPort connector that communicates uncompressed pixel values in packets through a DisplayPort cable having an auxiliary link and four data links. A switching device interfaced with the graphics connector selectively adapts the auxiliary link and data lines to communicate peripheral information between the display and the information handling systems, such as video from webcam, inputs from a mouse, or information from a transceiver connected as a peripheral to the display. A protocol selection controller associated with the switching device determines the protocol used by the peripheral and adapts one or more data links to communicate with the protocol, such as USB, 1394, SATA and PCIe protocols. In one embodiment, the protocol selection controller configures a data link to communicate in the selected protocol. In an alternative embodiment, the protocol selection controller includes identifier information with information sent across a data link so that information is communicated across the data link in plural protocols. A bandwidth negotiator monitors bandwidth demands of the graphics system to adjust the availability of data links for use in communication of peripheral information.
The present invention provides a number of important technical advantages. One example of an important technical advantage is that bandwidth in a display cable selectively allocates between display and peripheral protocols for more efficient communication of information between a display and information handling system. For example, data lanes of a DisplayPort cable automatically transition between communication of peripheral information and display information as an end user selects peripheral functions associated with a display, such as the use of a webcam, a mouse, a wireless transceiver or other peripheral operating in conjunction with the display. Switching peripheral and display data over all four data lines provides flexibility to respond to surges in data with minimal impact on performance, such as when motion-intensive images are presented at a display or files are transferred through a wireless transceiver at a display.
The present invention may be better understood, and its numerous objects, features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. The use of the same reference number throughout the several figures designates a like or similar element.
Data links of a DisplayPort cable are selectively adapted to communicate one or more of plural protocols to support interaction of peripherals coupled to a display with an information handling system coupled to the display. For purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, or other purposes. For example, an information handling system may be a personal computer, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include random access memory (RAM), one or more processing resources such as a central processing unit (CPU) or hardware or software control logic, ROM, and/or other types of nonvolatile memory. Additional components of the information handling system may include one or more disk drives, one or more network ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communications between the various hardware components.
Referring now to
During normal operations, graphics system 26 communicates pixel values to display 14 for presentation as visual images. In some instances, a peripheral interfaced with display 14 requests to send information through display cable 12 to information handling system 10. For example, peripherals interfaced with display 14 might include a webcam 38, a mouse 40, a wireless transceiver 42 or other types of peripherals. In one example embodiment, an end user who initiates a videoconference with webcam 38 causes webcam 38 to send a request through auxiliary link 32 to information handling system 10 for authorization to send images from webcam 38 through display cable 12 to chipset 22 for communication through a network interface of information handling system 10. Requests to send peripheral information through display cable 12 are sent from the peripheral to a peripheral selector 44 running as firmware on scalar 36 or other processing resources of display 14. Protocol selector determines the protocol for use with the peripheral and communicates the desired protocol to a protocol selection controller 46 of information handling system 10 through auxiliary link 32. In some instances, protocol selector 44 provides a list of protocols and associated transmission parameters to protocol selection controller 46 so that a protocol selection is available from plural available protocols to support communication with the peripheral based upon bandwidth available across display cable 12. Bandwidth negotiators 48 communicating through auxiliary link 32 negotiate for the amount of bandwidth available to communicate the peripheral information. In some instances, the amount of bandwidth changes as the images presented on display 14 change. For example, bandwidth negotiators 48 might assign all four data links 30 for transmission of peripheral information during a display refresh mode of operation or might use all four data links 30 for communicating pixel values when high resolution moving images are presented at display 14.
Once protocol selection controller 46 determines a protocol for communicating peripheral information through display cable 12, protocol selection controller 46 configures a switching device 50 of graphics connector 28 to establish the communication of peripheral information. A parallel process by protocol selector 44 is performed at display 14 with a switching device 50 of the display graphics connector 34. Switching device 50 communicates peripheral information over display cable 12 in several ways. In one embodiment, if adequate bandwidth exists to communicate display pixel values through less than all data links 30, protocol selection controller 46 assigns one or more data links 30 for exclusive use by the selected peripheral protocol. Alternatively, protocol selection controller 46 sends peripheral information in one direction on a data link 30 while sharing bandwidth of auxiliary link 32 to send peripheral information in the other direction. In another alternative embodiment, protocol selection controller 46 provides packet identification to send peripheral information for plural protocols and plural peripherals through a common data link 30. In yet another alternative embodiment, protocol selection controller 46 includes both display and peripheral information on a common data link 30.
Switching device 50 communicates information with graphics system 26 or chipset 22 based upon the protocol of the data link 30 that transmits the information or the identifier associated with the information. For example, if a data link 30 is assigned a peripheral protocol, then information received at switching device 50 from that data link 30 is switched to chipset 22. If a data link 30 is assigned to communicate display pixel values, then information received at switching device 50 from that data link 30 is switched to scalar 36. If a data link 30 or auxiliary link 32 is assigned to communicate both display and peripheral information, then an identifier of a simple header on each packet of information indicates to switching device 50 where to communicate the information. For example, DisplayPort packets are used to communicate all of the information by encapsulating information having other protocols and adding a short header that identifies the encapsulated protocol. This allows allocation of bandwidth across display cable 12 with greater granularity for improved usage of available bandwidth.
In an embodiment where DisplayPort data links are individually assigned peripheral protocols, the following table illustrates some examples of how information is communicated.
DisplayPort allows communication of different amounts of pixel values with 1, 2, or 4 data links configured to communicate display information. In one embodiment, an alternative type of display protocol may be used to communicate display information through DisplayPort data links so that no DisplayPort pixel values are sent. For instance, a DisplayPort data link configured to use the 1394 protocol can send display information to support presentation of visual images at a display. The auxiliary channel is available to communicate protocol selections between information handling system 10 and display 14 and can also provide shared bandwidth to support other protocols. For example, a PCIe data link sending peripheral information needs bi-lateral communication, however, the PCIe data communicated to the peripheral is typically minimal and may be sent over bandwidth shared with other protocols over other data links or the auxiliary link.
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Although the present invention has been described in detail, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the invention as defined by the appended claims.
