Update: May 13, 2014. This report turned out to be accurate, as VESA announced the addition of Adaptive Sync to their 1.2a in this press release today. This was required for AMD to utilize “Project Freesync” which will almost certainly make it into official drivers soon. This probably means the death of G-Sync, as just about every new monitor supporting DisplayPort 1.2a should support this feature. At the very least, Nvidia will probably have to make changes to G-Sync, allowing it to be used with VESA Adaptive Sync standards in addition to their own proprietary standards.
Details are a bit sketchy, since the only source is in French, but apparently VESA has accepted AMD’s proposal to change the specifications for DisplayPort 1.2A. Here is the original request that was made in November 2013, and reviewed in January 2014:
Extend the “MSA TIMING PARAMETER IGNORE” option to DisplayPort to enable source based control of the frame rate similar to embedded DisplayPort.
Intellectual property rights
Benefits as a result of changes
This enables the ability for external DisplayPort to take advantage of the option to ignore MSA timing parameter and have the sink slave to source timing to realize per frame dynamic refresh rate.
Assessment of the impact
The proposed change enable per frame dynamic refresh rate for single stream devices that expose dynamic refresh rate capability in EDID for DisplayPort interface. The source will be able to enable this with an SST interface or MST hub with physical ports. Logical MST port support of the feature is not included as part of this SCR. A generic framework to enable such feature for logical port is required that can accommodate other feature where stream related configuration is programmed in DPCD.
Analysis of the device software implication
SST device which support “MSA TIMING PARAMETER IGNORE” option will be able to expose the capability in EDID and DPCD to let source enable dynamic refresh rate.
Source driver would have to be updated to parse EDID and enable “MSA TIMING PARAMETER IGNORE” feature when source want the sink to be refreshed based on its update rate.
Analysis of the compliance test and interop implications
Currently this feature is tested as part of eDP CTS. New test would have to be added as part of DP LL CTS and EDID CTS.
Based on an unnamed source, hardware.fr (google translate) appears to have seen the response to this document, specifically mentioning it in the line “Extend DP1.2a MSA Tmg settings Ignore Option AMD”. This indicates that the specific option AMD requested has been accepted, and will be extended into the DisplayPort 1.2a specification.
This should mean that any display supporting DP1.2a should support the dynamic refresh rate that is required for AMD to make use of what they called “Freesync” when they showed it off at CES. This is a developing story, and we’ll be updating it as new information comes in.