External Monitor resolution (would like 3840x2160)

[Phillip Bell]

Hi all,

I've been doing searching on this forum, and I haven't found many good answers.  One or two threads closed, some others not really answering.  Here's my question:

PineBook Pro -> USB C adapter -> HDMI -> LG 43Un700-B

Resolution at 1920x1080 is supported on the external LG monitor

Problem: The monitor itself frequently suggests that I switch to 3840x2160

Question: Is this theoretically possible with PBP?

Datum: When I attempt this, I get a KDE error "Outputs could not be saved due to error"

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USB C to HDMI adapter:

CableCreation 5-in-1 USB C Adapter with 4K HDMI

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Log file snippet:

[ 17.761] (**) Option "xkb_options" "terminate:ctrl_alt_bksp"
[ 4107.965] (--) modeset(0): HDMI max TMDS frequency 300000KHz
[ 35899.567] (II) modeset(0): Allocate new frame buffer 3840x1080 stride
[ 35899.701] (EE) event0 - HAILUCK CO.,LTD USB KEYBOARD: client bug: event processing lagging behind by 138ms, your system is too slo
w
[ 35925.629] (EE) client bug: timer event8 debounce: scheduled expiry is in the past (-14ms), your system is too slow
[ 35925.629] (EE) client bug: timer event8 debounce short: scheduled expiry is in the past (-27ms), your system is too slow
[

[jiyong]

Theoretically, yes.
The Samsung Chromebook Plus has the same chip, the RK3399 and is capable to output a 4K signal.

But a Manjaro developer has the suspicion that Google applied some kernel patches in ChromeOS and it is not supported in the mainline kernel.
https://archived.forum.manjaro.org/t/pin.../148882/11

[Arwen]

@Phillip Bell - The device you bought seems to support 30hz refresh only @ 4K, if this is the device;

https://www.amazon.com/Multiport-Adapter...B08FWPKVBG

According to the LG web side, the monitor only supports 60hz refresh rate;

https://www.lg.com/us/monitors/lg-43un70...ed-monitor

Their is only so much bandwidth possible from earlier devices. This 5 in 1 has 1Gbps Ethernet, 3 x USB 3 ports and the DisplayPort to HDMI. This generally means that 2 of the high speed lanes are DisplayPort out, (2K @ 60hz or 4K @ 30hz), and the other pair is for USB 3.x. Which is then broken out by a USB 3 hub to the 3 x USB 3 and the 1Gbps Ethernet.

In essence, you need to buy a device that only has USB 2.x support and allows all 4 high speed lanes for DisplayPort. A while back I did see some devices with a switch on them, to allow changing from external display using 2 or 4 lanes. But, it's probably simpler to find a USB 2.x only device.

Remember, Pinebook Pro only supports DisplayPort out. What the external adapter device then uses for an external display connector, DisplayPort or actively translating to HDMI, is up to the external adapter device.

See this Wiki page for some ideas:

https://wiki.pine64.org/wiki/Pinebook_Pr...te_mode_DP

[Phillip Bell]

I did get this setup working with the hardware listed above, by using the following:

sudo pacman -Syyu linux-pinebookpro linux-pinebookpro-headers

But I agree with Arwen, I should be using DisplayPort - I wanted to save that for my Windows machine, but I'd like to see better performance on the PBP, anyway, so I can try it out.