Monitor Turns to a Black Screen When USB-C Prioritization Changes from High Data Speed to High Resolution
摘要: A ThinOS device connects to a monitor with a USB-C prioritization feature turns to black when changing the configuration from "High Data Speed" to "High Resolution."
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症狀
Affected Platforms:
- Dell Wyse 5070
- Dell Wyse 5470
Affected Products:
All monitors that support USB-C Prioritization:
- U4320Q
- U2520D
- U2421HF
- U2721DE
- U2421E
- U2422H
- U2422HE
- U2722D
- U2722DE
- P3222QE
- C2722DE
Affected Operating Systems:
- Dell ThinOS
Sample: USB-C Prioritization image - from U2520D monitor user guide
Figure 1 (English Only): USB-C Prioritization setting
How to Reproduce steps and behavior:
- Connect a monitor which has a USB-C prioritization feature to a DELL Wyse 5070 thin client USB type C port using a Type-C to Type-C cable.
- Power on the thin client and wait for the ThinOS desktop to display on the monitor properly.
- Press the monitor On Screen Display (OSD) menu and select USB-C prioritization.
- Change the setting from High Data Speed to High Resolution.
- The monitor screen turns black, and the OSD shows that there has been no USB-C signal input detected. This is the reason why the video cannot be displayed.
原因
ThinOS firmware does not support USB-C prioritization (this is due to the USB Type-C Connector System Software Interface (UCSI) specification). Hence, when the USB-C prioritization setting changes, the ports link training cannot properly establish to present the video on the monitor screen.
解析度
Work around
Force the thin client to restart.
Log term solution:
ThinOS 2311 (9.4.4106) or later resolves this issue.