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Be sure to read the update at the end, since the article is partly outdated with DisplayPort 1.4. With DP 1.4, only two lanes are necessary thanks to HBR3 (and
by danieldk 5y ago
Be sure to read the update at the end, since the article is partly outdated with DisplayPort 1.4. With DP 1.4, only two lanes are necessary thanks to HBR3 (and DSC). So, you can have 4k@60Hz while also having USB 3.1 Gen3 at 10Gbit/s.
E.g. I use a Lenovo USB-C Dock Gen 2, which supports this. You can have it all with just a single cable.
Unfortunately, Linux misconfigures the lanes (does not use HBR3) for this hub and apparently some other hubs [1], so 4K@60Hz is not supported using a single cable. Windows 10 works fine and my wife's MacBook as well.
[1] https://gitlab.freedesktop.org/drm/amd/-/issues/1317 https://gitlab.freedesktop.org/drm/amd/-/issues/1317
- Nextgrid 5y agoDoes this require cable/hub support? I've currently got a hub which provides USB3 ports as well as HDMI, and as expected, only goes up to 4k@30Hz. Would a simple software change & hardware support on the host side be enough, or does the hub still need to be upgraded?
- wmf 5y agoThat hub presumably has a DP-to-HDMI chip that will never support DP 1.4. HDMI isn't for monitors anyway...
- danieldk 5y agoIt's so annoying that many monitors (e.g. common LG models) have 1x DP and 2x HDMI.
- SECProto 5y agoI have a monitor with 1xDP and 2xHDMI and it's perfect. I use the DP for my desktop, one HDMI for my laptop dock, and the other HDMI for anything I might choose to use instead (console being the only thing I've used so far)
- vladvasiliu 5y agoI have one of those LG monitors, although mine has a usb-c input which also handles display-port (so it's 2xDP + 2xHDMI). What really bugs me with HDMI is that monitors and computers never seem to agree on the image standard and for some reason always default to washed-out colours, even when connecting a PC to a PC monitor (as opposed to a TV). Under Linux/X11 I know how to set it in full range mode [0], but I was using such a monitor at home and connected it the HDMI output of my gaming PC (Radeon GPU) and couldn't figure out how to fix the washed-out colours. In the end I bit the bullet and bought a display-port switch. Now windows complains about the "limited display connectivity" (the monitor has a USB hub whose upstream is the usb-c/dp connector), but at least the colours look OK. --- [0] `xrandr --output HDMI1 --set "Broadcast RGB" "Full"` IIRC
- danieldk 5y agoAt the very least it requires DP 1.3 support of both the dock/hub and the machine that it is hooked up to for HBR3 and DP 1.4 for DSC. If either uses an older version, it doesn't work. I don't know about HDMI, there is HDMI alt-mode, but I think many docks use DP-Alt mode for HDMI as well. tl;dr: requires support from the host and the dock.
- seba_dos1 5y ago> there is HDMI alt-mode, but I think many docks use DP-Alt mode for HDMI as well DP alt-mode is ubiquitous, while HDMI alt-mode support is very rare on both host and peripheral sides.
- thirtyseven 5y agoIf this is the case, then how does the Caldigit TS3 Plus dock (https://www.caldigit.com/ts3-plus/ https://www.caldigit.com/ts3-plus/) support 4K@60Hz video and USB 3.0 ports while only using DisplayPort 1.2?
- deleted 5y ago[deleted]
- Matthias247 5y agoIt uses Thunderbolt 3, not plain USB. Although sharing the same connector, these are different protocols
- EwanToo 5y agoThat's a thunderbolt dock, which has higher bandwidth than usb 3 and it's variants (usb4 mostly merges with thunderbolt 4 but not entirely)
- techrat 5y agoThunderbolt mode over USB C is basically a direct PCIe connection along with DP.
- tmobileuser 5y agoI’ve that exact set up right now and it works great! Kubuntu+thinkpad nano+2.0 dock+4K at 60hz
- danieldk 5y agoMaybe they issue only crops up on AMD APUs? Though, in the linked bug report, there is also someone who has an Intel Iris Xe GPU with the same issue.