Claims:1. A method, comprising:
transmitting a skew training pattern on a signal line including a differential pair; and
receiving an acknowledgment, related to the skew training pattern, on a display data channel (DDC) associated with an high-definition multimedia interface (HDMI) system.

2. The method according to claim 1, wherein the signal line is a transmission minimized differential signaling (TMDS) channel of the HDMI system.
, Description:TECHNICAL FIELD
[0001] Embodiments herein generally relate to high-definition multimedia interface (HDMI). More particularly, embodiments herein generally relate to skew correction communications in HDMI systems.

BACKGROUND
[0002] The digital interface technology HDMI (High Definition Multimedia Interface) is a leading standard for transmission of video signals and audio signals between devices, and has been widely used in the field of household electrical appliances and audiovisual devices. HDMI has been realized by further developing a digital visual interface (DVI) so that video signals, audio signals, and device control signals can be transmitted over a single cable.
[0003] Multiple versions of HDMI have been developed as bandwidth and/or other capabilities of audiovisual data transfer increase, with recent releases including HDMI versions 1.4 and 2.0. HDMI 2.0 supports a per-channel bandwidth of at least 6Gbps. This bandwidth allows for higher-resolution audio and video transfer compared to earlier HDMI versions.
[0004] Visual display units, flat screens, displays, mobile devices, computers, television sets and monitors supporting high resolutions may include an electrical connection interface, such as a DVI data transmitting interface and/or HDMI data transmitting interface. In addition to various control signals, several differential transition minimized differential signaling (TMDS) encoded signals for the transmission of audio and video data as well as required clock signaling between at least one data source and at least one data sink are carried via this interface.
[0005] HDMI systems my operate in native or non-native mode. In particular, HDMI standards specify that native TMDS operation requires a 3.3 line voltage. However, some HDMI systems may not support the 3.3V requirement. Such HDMI systems are known as non-native.
[0006] The HDMI standards use three separate TMDS channels for the additive primary colors used in creating displayed video images. These signals are transmitted at a very high rate (GHz range). Even a small change in the propagation characteristics of the copper conductors used to carry the components can cause signal glitches. Intra-pair skew is defined as a difference in propagation speed between the positive and negative lines in a differential pair. A slight difference in arrival times for the two components of a pair can cause a data bit to fall outside of the decision boundary defined for that bit. For example, digital high signals can then become low and vice-versa.
[0007] Some non-native implementations make use of active level shifters (ALS) to compensate for skew associated with differential signal lines. However, use of ALS adds expense to HDMI systems.