Devices, systems, and methods for instant video switching in an extension environment
Extension devices such as upstream facing port devices (UFP devices) and downstream facing port devices (DFP devices) connect via an extension medium. When a UFP device and a DFP device pair with each other, DisplayPort video and/or audio information from a DisplayPort source device can be presented by a DisplayPort sink device, which are coupled to the UFP device and DFP device, respectively. In some embodiments, the DFP device may train a DisplayPort link to the DisplayPort sink device regardless of whether it is receiving actual data from a UFP device, and may provide placeholder data to the DisplayPort sink device in order to keep the link active. The DFP device may then replace the placeholder data with the actual data from the UFP device, once received, and may thereby seamlessly switch the DisplayPort sink device from presenting placeholder data to presenting data from the DisplayPort source device.
1. A method of switching DisplayPort connections over an extension medium, the method comprising:
conducting, by a downstream facing port (DFP) device, link training with a DisplayPort sink device coupled to the DFP device;
transmitting, by the DFP device, DisplayPort data to the DisplayPort sink device that includes first actual video data received from an extension medium by the DFP device, wherein the first actual video data is received from a first extension device connected to a first DisplayPort source device;
receiving, by the DFP device, a command to pair to a second extension device connected to a second DisplayPort source device; and
transmitting, by the DFP device, DisplayPort data that includes second actual video data received from the second extension device instead of the first actual video data to the DisplayPort sink device without re-training the link between the DFP device and the DisplayPort sink device.
2. The method of claim 1 , wherein the first actual video data and the second actual video data have identical timing.
3. The method of claim 1 , wherein timing of the first actual video data and timing of the second actual video data is different, and wherein method further comprises:
generating, by the DFP device, DisplayPort data that includes at least five idle patterns; and
transmitting, by the DFP device, the DisplayPort data that includes at least five idle patterns between the DisplayPort data that includes the first actual video data and the DisplayPort data that includes the second actual video data.
4. The method of claim 1 , further comprising:
transmitting, by the DFP device, DisplayPort data that includes placeholder video data generated by the DFP device to the DisplayPort sink device; and
switching, by the DFP device, to transmitting the DisplayPort data to the DisplayPort sink device that includes the first actual video data instead of the placeholder video data without conducting link training again.
5. The method of claim 4 , wherein timing of the placeholder video data and timing of the first actual video data is identical.
6. The method of claim 4 , further comprising:
using the first actual video data received from the extension medium to generate the DisplayPort data that includes the first actual video data; and
using the placeholder video data generated by the DFP device to generate the DisplayPort data that includes the placeholder video data.
7. A downstream facing port device (DFP device), comprising:
an extension interface;
a DisplayPort interface configured to receive actual video data from the extension interface, wherein the actual video data is generated by a DisplayPort source device; and
a downstream video engine configured to:
conduct link training with a DisplayPort sink device coupled to the DisplayPort interface;
transmit DisplayPort data that includes first actual video data to the DisplayPort sink device, wherein the first actual video data is received from a first extension device connected to a first DisplayPort source device;
receive a command to pair to a second extension device connected to a second DisplayPort source device; and
transmit DisplayPort data that includes second actual video data received from the second extension device instead of the first actual video data to the DisplayPort sink device without re-training the link between the DFP device and the DisplayPort sink device.
8. The DFP device of claim 7 , wherein the first actual video data and the second actual video data have identical timing.
9. The DFP device of claim 7 , wherein timing of the first actual video data and timing of the second actual video data is different, and wherein the downstream video engine is further configured to:
generate DisplayPort data that includes at least five idle patterns; and
transmit the DisplayPort data that includes at least five idle patterns between the DisplayPort data that includes the first actual video data and the DisplayPort data that includes the second actual video data.
10. The DFP device of claim 7 , further comprising a placeholder video engine configured to generate placeholder video data, wherein the downstream video engine is further configured to:
transmit DisplayPort data that includes the placeholder video data to the DisplayPort sink device; and
switch to transmitting DisplayPort data that includes the first actual video data instead of the placeholder video data to the DisplayPort sink device without conducting link training again.
11. The DFP device of claim 10 , wherein timing of the first actual video data and timing of the placeholder video data is identical.
12. The DFP device of claim 10 , wherein the downstream video engine is further configured to:
use the placeholder video data generated by the placeholder video engine to generate the DisplayPort data that includes the placeholder video data; and
use the first actual video data received by the extension interface to generate the DisplayPort data that includes the first actual video data.
13. A non-transitory computer-readable medium having computer-executable instructions stored thereon that, in response to execution by one or more processors of a downstream facing port (DFP) device, cause the DFP device to perform actions for switching DisplayPort connections over an extension medium, the actions comprising:
conducting, by the DFP device, link training with a DisplayPort sink device coupled to the DFP device;
transmitting DisplayPort data to the DisplayPort sink device that includes first actual video data received from an extension medium by the DFP device, wherein the first actual video data is received from a first extension device connected to a first DisplayPort source device;
receiving, by the DFP device, a command to pair to a second extension device connected to a second DisplayPort source device; and
transmitting, by the DFP device, DisplayPort data that includes second actual video data received from the second extension device instead of the first actual video data to the DisplayPort sink device without re-training the link between the DFP device and the DisplayPort sink device.
14. The computer-readable medium of claim 13 , wherein the first actual video data and the second actual video data have identical timing.
15. The computer-readable medium of claim 13 , wherein timing of the first actual video data and timing of the second actual video data is different, and wherein the actions further comprise:
generating, by the DFP device, DisplayPort data that includes at least five idle patterns; and
transmitting, by the DFP device, the DisplayPort data that includes at least five idle patterns between the DisplayPort data that includes the first actual video data and the DisplayPort data that includes the second actual video data.
16. The computer-readable medium of claim 13 , wherein the actual video data is first actual video data received from a first extension device connected to a first DisplayPort source device, and wherein the actions further comprise:
transmitting, by the DFP device, DisplayPort data that includes placeholder video data generated by the DFP device to the DisplayPort sink device; and
switching, by the DFP device, to transmitting the DisplayPort data to the DisplayPort sink device that includes the first actual video data instead of the placeholder video data without conducting link training again.
17. The computer-readable medium of claim 16 , wherein timing of the first actual video data and timing of the placeholder video data is identical.
18. The computer-readable medium of claim 16 , wherein the actions further comprise:
using the placeholder video data generated by the DPF device to generate the DisplayPort data that includes the placeholder video data; and
using the first actual video data received from the extension medium to generate the DisplayPort data that includes the first actual video data.