** Package changed: ubuntu => xorg (Ubuntu) -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/2109692
Title: Failed automatic external monitor detection Status in xorg package in Ubuntu: New Bug description: Hello, I am experiencing an issue with automatic external monitor detection when connected via a Dell Pro Thunderbolt 4 Dock (SD25TB4) on my Dell Precision 5490 laptop, running Ubuntu 24.04.2 LTS. The external monitor (connected via DisplayPort on the dock) is not automatically detected by the system when the laptop starts or when I connect the dock with the monitor already plugged in. The xrandr --listmonitors command initially only lists the laptop's built-in screen. However, the external monitor works correctly if, after the system has booted and the dock is connected, I manually unplug and re-plug ONLY the DisplayPort cable on the docking station. This action triggers the detection and activation of the display. Hardware Information: Laptop: Dell Precision 5490 Docking Station: Dell Pro Thunderbolt 4 Smart Dock (SD25TB4) External Monitor: [Brand and Model of the Monitor, if known - ADD THIS INFORMATION] Monitor -> Dock Connection: DisplayPort Laptop -> Dock Connection: Thunderbolt 4 / USB-C Thunderbolt Dock Identification: ● Dell Thunderbolt 4 Dock ├─ type: peripheral ├─ name: Dell Thunderbolt 4 Dock ├─ vendor: Dell ├─ uuid: [ANONYMIZED_UUID] ├─ generation: USB4 ├─ status: authorized │ ├─ domain: [ANONYMIZED_UUID] │ ├─ rx speed: 40 Gb/s = 2 lanes * 20 Gb/s │ ├─ tx speed: 40 Gb/s = 2 lanes * 20 Gb/s │ └─ authflags: none ├─ authorized: [DATE_ANONYMIZED] ├─ connected: [DATE_ANONYMIZED] └─ stored: [DATE_ANONYMIZED] ├─ policy: iommu └─ key: no (Note: Output shows the dock is authorized and connected). Software Information: Linux Distribution: Ubuntu 24.04.2 LTS Linux Kernel Version: 6.11.0-24-generic Intel Graphics Driver: i915 (confirmed by lspci) NVIDIA Graphics Driver: nvidia (proprietary driver, confirmed by lspci) NVIDIA Driver Version: nvidia-driver-570-open Optimus Graphics Mode: on-demand (confirmed by prime-select query). Testing nvidia exclusive mode did not resolve automatic detection at boot. bolt Version : 0.9.7-1 xrandr Version: 1.5.2 Steps to Reproduce the Bug: Connect the Dell SD25TB4 docking station to the Dell Precision 5490 laptop using the Thunderbolt/USB-C cable. Connect the external monitor to the docking station via DisplayPort. Boot the laptop into Linux (Ubuntu 24.04.2 LTS). After the graphical session loads, observe that the external monitor is not detected (it remains black/in standby). Open a terminal and run xrandr --listmonitors (it will only list the internal display). Expected Behavior: The external monitor should be automatically detected by the Linux system at boot or shortly after connecting the docking station and enabled according to display settings. Observed Behavior: The external monitor is not automatically detected at boot or dock connection. Workaround: The issue can be resolved by manually unplugging and re-plugging ONLY the DisplayPort cable on the docking station after the system has booted. The monitor is then immediately detected and works. Additional Diagnostic Information : ❯ lspci -k | grep -A 2 -E "(VGA|3D)" 00:02.0 VGA compatible controller: Intel Corporation Meteor Lake-P [Intel Arc Graphics] (rev 08) Subsystem: Dell Meteor Lake-P [Intel Arc Graphics] Kernel driver in use: i915 -- 01:00.0 3D controller: NVIDIA Corporation AD107GLM [RTX 1000 Ada Generation Laptop GPU] (rev a1) Subsystem: Dell Device 0cc7 Kernel driver in use: nvidia Finding regarding dmesg / journalctl logs: We attempted to capture kernel logs (sudo dmesg -C followed by sudo dmesg -k or sudo journalctl --since ...) while performing the action of replugging the DisplayPort cable that makes the display work. Despite the manual action triggering detection, these logs showed NO relevant messages or standard display hotplug events related to the drm, nvidia, i915, thunderbolt, usb4, DP, DisplayPort, EDID, connector, or hotplug layers at the time of the manual action. This seems to indicates that the low-level detection event is not being correctly signaled or logged. We dont really know why. Output of lsusb : (Shows dock's USB components are detected) ❯ lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 002 Device 002: ID 8087:0b40 Intel Corp. USB3.0 Hub Bus 002 Device 003: ID 0bda:0480 Realtek Semiconductor Corp. 4-Port USB 3.0 Hub Bus 002 Device 004: ID 0bda:0485 Realtek Semiconductor Corp. 4-Port USB 3.0 Hub Bus 002 Device 005: ID 0bda:0481 Realtek Semiconductor Corp. USB3.2 Hub Bus 002 Device 006: ID 0bda:8156 Realtek Semiconductor Corp. USB 10/100/1G/2.5G LAN Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 003 Device 003: ID 8086:0b63 Intel Corp. USB Bridge Bus 003 Device 004: ID 27c6:634c Shenzhen Goodix Technology Co.,Ltd. Goodix Fingerprint USB Device Bus 003 Device 006: ID 1d5c:5801 Fresco Logic USB2.0 Hub Bus 003 Device 007: ID 0bda:5480 Realtek Semiconductor Corp. 4-Port USB 2.0 Hub Bus 003 Device 008: ID 413c:b0a4 Dell Computer Corp. HID GENERIC DEVICE Bus 003 Device 009: ID 0bda:5485 Realtek Semiconductor Corp. 4-Port USB 2.0 Hub Bus 003 Device 010: ID 0bda:5481 Realtek Semiconductor Corp. USB2.1 Hub Bus 003 Device 011: ID 413c:b0a2 Dell Computer Corp. USB2.0 HID Bus 003 Device 012: ID 413c:b0a3 Dell Computer Corp. USB2.0 HID Bus 003 Device 013: ID 413c:b0a5 Dell Computer Corp. VMM8431 Bus 003 Device 014: ID 413c:b06e Dell Computer Corp. K2 DOCK HID Bus 003 Device 015: ID 413c:b0a1 Dell Computer Corp. HID Device Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Impact: This bug makes the daily use of the external monitor via the docking station inconvenient, requiring a manual intervention (unplugging/re- plugging the DisplayPort cable) with each connection or restart. 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