Running "sudo xdiagnose" provided useful results, showing that the retrievel of EDID information fails:
[26303.206855] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up [26303.528370] usb 3-3.1: new SuperSpeed USB device number 6 using xhci_hcd [26303.756236] usb 2-3.1: new high-speed USB device number 17 using xhci_hcd [26303.776483] usb 3-3.1: New USB device found, idVendor=2109, idProduct=0812 [26303.776486] usb 3-3.1: New USB device strings: Mfr=1, Product=2, SerialNumber=0 [26303.776488] usb 3-3.1: Product: OneLink Pro Dock [26303.776489] usb 3-3.1: Manufacturer: LENOVO [26303.778523] hub 3-3.1:1.0: USB hub found [26303.778650] hub 3-3.1:1.0: 4 ports detected [26303.822991] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up [26303.857614] usb 2-3.1: New USB device found, idVendor=2109, idProduct=2812 [26303.857617] usb 2-3.1: New USB device strings: Mfr=1, Product=2, SerialNumber=0 [26303.857619] usb 2-3.1: Product: OneLink Pro Dock [26303.857620] usb 2-3.1: Manufacturer: LENOVO [26303.858249] hub 2-3.1:1.0: USB hub found [26303.858390] hub 2-3.1:1.0: 4 ports detected [26304.148234] usb 2-3.1.1: new full-speed USB device number 18 using xhci_hcd [26304.148261] usb 3-3.1.3: new SuperSpeed USB device number 7 using xhci_hcd [26304.164799] usb 3-3.1.3: New USB device found, idVendor=17ef, idProduct=304f [26304.164806] usb 3-3.1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [26304.164808] usb 3-3.1.3: Product: ThinkPad Dock Giga [26304.164809] usb 3-3.1.3: Manufacturer: Lenovo [26304.164811] usb 3-3.1.3: SerialNumber: 0050B67951C2 [26304.167588] cdc_ether 3-3.1.3:2.0 eth1: register 'cdc_ether' at usb-0000:00:14.0-3.1.3, CDC Ethernet Device, 00:50:b6:79:51:c2 [26304.169545] cdc_ether 3-3.1.3:2.0 eth1: unregister 'cdc_ether' usb-0000:00:14.0-3.1.3, CDC Ethernet Device [26304.255321] usb 2-3.1.1: New USB device found, idVendor=0711, idProduct=0230 [26304.255324] usb 2-3.1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [26304.255326] usb 2-3.1.1: Product: USB Ver1.2 Device [26304.255327] usb 2-3.1.1: Manufacturer: USB-RS232 Interface Converter [26304.255329] usb 2-3.1.1: SerialNumber: 015109 [26304.257332] mct_u232 2-3.1.1:1.0: MCT U232 converter detected [26304.257544] usb 2-3.1.1: MCT U232 converter now attached to ttyUSB0 [26304.296535] usb 3-3.1.3: reset SuperSpeed USB device number 7 using xhci_hcd [26304.340692] usb 2-3.1.2: new high-speed USB device number 19 using xhci_hcd [26304.341183] r8152 3-3.1.3:1.0 eth1: v1.08.2 [26304.439934] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up [26304.440407] usb 2-3.1.2: New USB device found, idVendor=05ac, idProduct=911c [26304.440409] usb 2-3.1.2: New USB device strings: Mfr=0, Product=0, SerialNumber=0 [26304.442065] hub 2-3.1.2:1.0: USB hub found [26304.442124] hub 2-3.1.2:1.0: 3 ports detected [26304.712204] usb 2-3.1.2.2: new full-speed USB device number 20 using xhci_hcd [26305.059084] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up [26305.502533] IPv6: ADDRCONF(NETDEV_UP): eth1: link is not ready [26305.556248] IPv6: ADDRCONF(NETDEV_UP): eth1: link is not ready [26305.675478] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up [26306.060130] usb 2-3.1.4: new full-speed USB device number 21 using xhci_hcd [26306.165899] usb 2-3.1.4: config 1 interface 1 altsetting 1 has 2 endpoint descriptors, different from the interface descriptor's value: 1 [26306.168414] usb 2-3.1.4: New USB device found, idVendor=17ef, idProduct=304e [26306.168417] usb 2-3.1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=0 [26306.168419] usb 2-3.1.4: Product: ThinkPad OneLink Pro Dock Audio [26306.168421] usb 2-3.1.4: Manufacturer: C-Media Electronics Inc. [26306.187250] input: C-Media Electronics Inc. ThinkPad OneLink Pro Dock Audio as /devices/pci0000:00/0000:00:14.0/usb2/2-3/2-3.1/2-3.1.4/2-3.1.4:1.3/0003:17EF:304E.0007/input/input20 [26306.187570] hid-generic 0003:17EF:304E.0007: input,hidraw0: USB HID v1.00 Device [C-Media Electronics Inc. ThinkPad OneLink Pro Dock Audio] on usb-0000:00:14.0-3.1.4/input3 [26306.290685] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up [26306.906238] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up [26306.906466] [drm:intel_dp_link_training_channel_equalization [i915]] *ERROR* failed to train DP, aborting [26306.916308] [drm:intel_dp_link_training_channel_equalization [i915]] *ERROR* Timed out waiting for DP idle patterns [26307.517170] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up [26308.133160] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up [26308.750067] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up [26309.365515] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up [26309.981216] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up [26310.569855] IPv6: ADDRCONF(NETDEV_CHANGE): eth1: link becomes ready [26310.609166] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up [26311.230512] [drm:intel_dp_link_training_clock_recovery [i915]] *ERROR* too many voltage retries, give up [26311.230744] [drm:intel_dp_link_training_channel_equalization [i915]] *ERROR* failed to train DP, aborting [26311.241886] [drm:intel_dp_link_training_channel_equalization [i915]] *ERROR* Timed out waiting for DP idle patterns [26314.831488] usb 2-3.1.2.2: New USB device found, idVendor=05ac, idProduct=921c [26314.831491] usb 2-3.1.2.2: New USB device strings: Mfr=1, Product=2, SerialNumber=0 [26314.831504] usb 2-3.1.2.2: Product: Apple Cinema HD Display [26314.831506] usb 2-3.1.2.2: Manufacturer: Apple Computer, Inc. [26314.837511] hid-generic 0003:05AC:921C.0008: hiddev0,hidraw1: USB HID v1.11 Device [Apple Computer, Inc. Apple Cinema HD Display] on usb-0000:00:14.0-3.1.2.2/input0 [26315.267422] lenovo 0005:17EF:6048.0009: unknown main item tag 0x0 [26315.267665] input: ThinkPad Compact Bluetooth Keyboard with TrackPoint as /devices/pci0000:00/0000:00:14.0/usb2/2-7/2-7:1.0/bluetooth/hci0/hci0:256/0005:17EF:6048.0009/input/input21 [26315.268411] lenovo 0005:17EF:6048.0009: input,hidraw2: BLUETOOTH HID v3.09 Keyboard [ThinkPad Compact Bluetooth Keyboard with TrackPoint] on 60:57:18:0c:4a:67 [26316.523716] hid-generic 0005:0A5C:0001.000A: unknown main item tag 0x0 [26316.523778] input: Kensington SureTrack Mouse as /devices/pci0000:00/0000:00:14.0/usb2/2-7/2-7:1.0/bluetooth/hci0/hci0:512/0005:0A5C:0001.000A/input/input22 [26316.524025] hid-generic 0005:0A5C:0001.000A: input,hidraw3: BLUETOOTH HID v1.29 Mouse [Kensington SureTrack Mouse] on 60:57:18:0c:4a:67 [26330.908156] [drm:drm_edid_block_valid [drm]] *ERROR* EDID checksum is invalid, remainder is 40 [26330.908159] Raw EDID: [26330.908160] 00 ff ff ff ff ff ff 00 4c 2d 3f 04 34 32 59 4d [26330.908161] 02 13 01 03 80 34 20 78 2a ee 91 a3 54 4c 99 26 [26330.908162] 0f 50 54 ff ff ff ff ff ff ff ff ff ff ff ff ff [26330.908163] ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff [26330.908164] ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff [26330.908165] ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff [26330.908166] ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff [26330.908167] ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1565667 Title: When returning from suspend, my external Apple monitor is not detected, and nothing I do seem to enable it. Rebooting makes everything work as it should. This was not a problem on 15.10. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1565667/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
