An easy to use EDID editor that describes the various bits for the user is another very important and time-saving tool. The resolution, the video mode used, the color format, the audio format, etc.īy altering the EDID of a test sink the engineer can easily verify the flexibility of the sink. This data is the basis for the source when it is selecting the format of the content that will be sent to the sink. Important for the DP source-sink communication is that the EDID defines the native resolution of the sink and the video modes that the sink supports. Reading the sink EDID data is one of the first acts that the source is doing once connected to the sink. It defines the make and the model name, the screen size, and the color format. EDIDĮxtended display identification data (EDID) is a bock of structured data defining the capabilities of the DP sink. Therefore it is essential for the productivity of the DP debug process that the tool used readily parses DPCD content in AUX Reads and writes to the terminology commonly used by e.g. Recalling the detailed meaning of each bit in the tens of DPCD registers is challenging. During the process of establishing the data links, the Link Training, source writes to DPCD to indicate the target link configuration and sink in turn whites there the result of each link training stage. The message transfer between DP source and sink occur by reads and writes to the DisplayPort Configuration Data (DPCD) register of the sink device.īy reading certain registers in the DPCD, the source will be aware of the capabilities of the sink. An AUX Channel Monitor tool is must-have equipment for all designers of DP protocol related engineers. Since the AUX Channel is the key element in the source/sink communication, the core to understanding the handshake process is logging the AUX Channel communication. The only way how the sink can communicate with the source is by issuing a pulse in the Hot Plug Detect (HPD) signal. Since the source device controls the process, it makes requests for the sink. AUX Channelįor the handshake between the source and the sink, DP has a dedicated bus, the AUX Channel. Please find below brief definitions of the basic functions of the DP interface and the issues to verify during debugging. Also, the handshake before the connection is much more comprehensive than just plug-in. Multimedia content transfer in DP Main Data Links is resembling a data link more than e.g. Before video and audio content is sent over a DP link and displayed on the monitor screen a lot of communication has been occurring between a DP source and sink and a possible branch device.
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