On Dell XPS 9350 (2016 model) you need to use the USB-C port if you want to enjoy a external monitor. One of the USB-C adaptors is Dell Adapter - USB-C to HDMI/VGA/Ethernet/USB 3.0 (DA200).
When I connect the adapter on the machine I have
$ dmesg
[426949.056524] hub 4-0:1.0: USB hub found
[426949.056543] hub 4-0:1.0: 2 ports detected
[426949.417197] usb 3-1: new high-speed USB device number 2 using xhci_hcd
[426949.599546] hub 3-1:1.0: USB hub found
[426949.600098] hub 3-1:1.0: 4 ports detected
[426949.695244] usb 4-1: new SuperSpeed USB device number 2 using xhci_hcd
[426949.712836] hub 4-1:1.0: USB hub found
[426949.713151] hub 4-1:1.0: 4 ports detected
[426949.878311] usb 3-1.3: new full-speed USB device number 3 using xhci_hcd
[426949.960668] usb 3-1.3: config 1 has no interfaces?
[426950.025168] usb 4-1.4: new SuperSpeed USB device number 3 using xhci_hcd
[426950.115300] usb 4-1.4: reset SuperSpeed USB device number 3 using xhci_hcd
[426950.156378] r8152 4-1.4:1.0 eth0: v1.08.3
[426951.795777] r8152 4-1.4:1.0 enp57s0u1u4: renamed from eth0
$ xrandr
Screen 0: minimum 8 x 8, current 3200 x 1800, maximum 32767 x 32767
eDP1 connected primary 3200x1800+0+0 (normal left inverted right x axis y axis) 290mm x 170mm
3200x1800 59.98*+ 47.99
2880x1620 60.00
2560x1440 60.00
2048x1536 60.00
1920x1440 60.00
1856x1392 60.01
1792x1344 60.01
2048x1152 60.00
1920x1080 60.00
1600x1200 60.00
1400x1050 59.98
1600x900 60.00
1280x1024 60.02
1280x960 60.00
1368x768 60.00
1280x720 60.00
1024x768 60.00
1024x576 60.00
960x540 60.00
800x600 60.32 56.25
864x486 60.00
640x480 59.94
720x405 60.00
640x360 60.00
DP1 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
I can connect an external monitor using the HDMI port and I will get
$ xrandr
Screen 0: minimum 8 x 8, current 3200 x 1800, maximum 32767 x 32767
eDP1 connected primary 3200x1800+0+0 (normal left inverted right x axis y axis) 290mm x 170mm
3200x1800 59.98*+ 47.99
2880x1620 60.00
2560x1440 60.00
2048x1536 60.00
1920x1440 60.00
1856x1392 60.01
1792x1344 60.01
2048x1152 60.00
1920x1080 60.00
1600x1200 60.00
1400x1050 59.98
1600x900 60.00
1280x1024 60.02
1280x960 60.00
1368x768 60.00
1280x720 60.00
1024x768 60.00
1024x576 60.00
960x540 60.00
800x600 60.32 56.25
864x486 60.00
640x480 59.94
720x405 60.00
640x360 60.00
DP1 connected (normal left inverted right x axis y axis)
1920x1080 60.00 + 50.00 59.94
1920x1080i 60.00 50.00 59.94
1280x1024 75.02 60.02
1152x864 75.00
1280x720 60.00 50.00 59.94
1024x768 75.03 60.00
800x600 75.00 60.32
720x576 50.00
720x480 60.00 59.94
640x480 75.00 60.00 59.94
720x400 70.08
DP2 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
Except for the external monitor doesn't work with high resolutions everything else works as expected.
And I can connect another external monitor using the VGA port. Now I will get
$ xrandr
Screen 0: minimum 8 x 8, current 3200 x 1800, maximum 32767 x 32767
eDP1 connected primary 3200x1800+0+0 (normal left inverted right x axis y axis) 290mm x 170mm
3200x1800 59.98*+ 47.99
2880x1620 60.00
2560x1440 60.00
2048x1536 60.00
1920x1440 60.00
1856x1392 60.01
1792x1344 60.01
2048x1152 60.00
1920x1080 60.00
1600x1200 60.00
1400x1050 59.98
1600x900 60.00
1280x1024 60.02
1280x960 60.00
1368x768 60.00
1280x720 60.00
1024x768 60.00
1024x576 60.00
960x540 60.00
800x600 60.32 56.25
864x486 60.00
640x480 59.94
720x405 60.00
640x360 60.00
DP1 connected (normal left inverted right x axis y axis)
1680x1050 59.95 +
1280x1024 75.02 60.02
1152x864 75.00
1024x768 75.03 60.00
800x600 75.00 60.32
640x480 75.00 59.94
720x400 70.08
DP2 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
The monitor connected on the VGA port works but the monitor connected on the HDMI doesn't work anymore.
From xrandr output we can see that both HDMI and VGA ports are using xrandr DP1 stream. Why? Can I change any configuration to be able to use both ports at the same time?
Note: As show in the picture below, I had to cut out one of the screws of the VGA adaptor.
Machine configuration
$ lspci
00:00.0 Host bridge: Intel Corporation Skylake Host Bridge/DRAM Registers (rev 09)
00:02.0 VGA compatible controller: Intel Corporation Skylake Integrated Graphics (rev 0a)
00:04.0 Signal processing controller: Intel Corporation Skylake Processor Thermal Subsystem (rev 09)
00:14.0 USB controller: Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller (rev 21)
00:14.2 Signal processing controller: Intel Corporation Sunrise Point-LP Thermal subsystem (rev 21)
00:15.0 Signal processing controller: Intel Corporation Sunrise Point-LP Serial IO I2C Controller #0 (rev 21)
00:15.1 Signal processing controller: Intel Corporation Sunrise Point-LP Serial IO I2C Controller #1 (rev 21)
00:16.0 Communication controller: Intel Corporation Sunrise Point-LP CSME HECI #1 (rev 21)
00:17.0 RAID bus controller: Intel Corporation 82801 Mobile SATA Controller [RAID mode] (rev 21)
00:1c.0 PCI bridge: Intel Corporation Device 9d10 (rev f1)
00:1c.4 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #5 (rev f1)
00:1c.5 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #6 (rev f1)
00:1d.0 PCI bridge: Intel Corporation Device 9d18 (rev f1)
00:1f.0 ISA bridge: Intel Corporation Sunrise Point-LP LPC Controller (rev 21)
00:1f.2 Memory controller: Intel Corporation Sunrise Point-LP PMC (rev 21)
00:1f.3 Audio device: Intel Corporation Sunrise Point-LP HD Audio (rev 21)
00:1f.4 SMBus: Intel Corporation Sunrise Point-LP SMBus (rev 21)
01:00.0 PCI bridge: Intel Corporation DSL5110 Thunderbolt Bridge [Falcon Ridge LP 2014]
02:00.0 PCI bridge: Intel Corporation DSL5110 Thunderbolt Bridge [Falcon Ridge LP 2014]
02:01.0 PCI bridge: Intel Corporation DSL5110 Thunderbolt Bridge [Falcon Ridge LP 2014]
02:02.0 PCI bridge: Intel Corporation DSL5110 Thunderbolt Bridge [Falcon Ridge LP 2014]
39:00.0 USB controller: Intel Corporation Device 15b5
3a:00.0 Network controller: Broadcom Corporation BCM4350 802.11ac Wireless Network Adapter (rev 08)
3b:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS525A PCI Express Card Reader (rev 01)
3c:00.0 Non-Volatile memory controller: Toshiba America Info Systems Device 010f (rev 01)
System configuration
Kernel 4.6.2
