El segundo monitor ya no funciona en Ubuntu 14.04

El segundo monitor ya no funciona en Ubuntu 14.04

Mi computadora portátil es una Acer Aspire M y solía conectar un segundo monitor a través de HDMI con regularidad. Hace aproximadamente un mes, simplemente dejó de funcionar. Realmente no sé nada que pueda hacer, por lo que cualquier ayuda sería muy apreciada.

Hoy noté que cuando estaba conectando el segundo monitor, aparecían los siguientes mensajes en TTY1, que también encontré en kern.log

Jul 25 17:38:44 CNPq-Universal-2013 kernel: [122775.342394] ACPI: \_SB_.PCI0: Bus check notify on hotplug_event_root
Jul 25 17:38:44 CNPq-Universal-2013 kernel: [122775.800703] [drm:intel_dp_start_link_train] *ERROR* too many voltage retries, give up
Jul 25 18:41:15 CNPq-Universal-2013 kernel: [126528.997425] ACPI: \_SB_.PCI0: Bus check notify on hotplug_event_root
Jul 25 18:41:16 CNPq-Universal-2013 kernel: [126529.453129] [drm:intel_dp_start_link_train] *ERROR* too many voltage retries, give up
Jul 25 19:24:42 CNPq-Universal-2013 kernel: [129136.555803] ACPI: \_SB_.PCI0: Bus check notify on hotplug_event_root
Jul 25 19:24:42 CNPq-Universal-2013 kernel: [129137.016462] [drm:intel_dp_start_link_train] *ERROR* too many voltage retries, give up
Jul 25 19:30:39 CNPq-Universal-2013 kernel: [129493.589703] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:30:39 CNPq-Universal-2013 kernel: [129493.711272] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:30:39 CNPq-Universal-2013 kernel: [129493.736376] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:30:39 CNPq-Universal-2013 kernel: [129493.736391] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:30:39 CNPq-Universal-2013 kernel: [129493.761667] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:32:06 CNPq-Universal-2013 kernel: [129580.669767] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:32:06 CNPq-Universal-2013 kernel: [129580.763589] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:32:06 CNPq-Universal-2013 kernel: [129580.788761] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:32:06 CNPq-Universal-2013 kernel: [129580.788778] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:32:06 CNPq-Universal-2013 kernel: [129580.814130] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:02 CNPq-Universal-2013 kernel: [129636.517006] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:02 CNPq-Universal-2013 kernel: [129636.541971] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:02 CNPq-Universal-2013 kernel: [129636.541981] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:11 CNPq-Universal-2013 kernel: [129646.293981] Watchdog[2574]: segfault at 0 ip 00007fea75b0eb88 sp 00007fea66d22720 error 6 in libcontent.so[7fea753aa000+fd7000]
Jul 25 19:33:15 CNPq-Universal-2013 kernel: [129650.199365] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:15 CNPq-Universal-2013 kernel: [129650.263559] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:15 CNPq-Universal-2013 kernel: [129650.288593] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:15 CNPq-Universal-2013 kernel: [129650.288688] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:16 CNPq-Universal-2013 kernel: [129650.515649] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:21 CNPq-Universal-2013 kernel: [129655.576538] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:25 CNPq-Universal-2013 kernel: [129659.687743] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:25 CNPq-Universal-2013 kernel: [129659.713246] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:25 CNPq-Universal-2013 kernel: [129659.713313] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:25 CNPq-Universal-2013 kernel: [129659.787798] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:34 CNPq-Universal-2013 kernel: [129668.757269] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:34 CNPq-Universal-2013 kernel: [129668.823856] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:34 CNPq-Universal-2013 kernel: [129668.848773] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:34 CNPq-Universal-2013 kernel: [129668.848824] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:33:34 CNPq-Universal-2013 kernel: [129669.076025] [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, remainder is 248
Jul 25 19:34:16 CNPq-Universal-2013 kernel: [129711.120207] Watchdog[10511]: segfault at 0 ip 00007fc2caa07b88 sp 00007fc2bbc1b720 error 6 in libcontent.so[7fc2ca2a3000+fd7000]

Vi a otra persona publicando estos detalles, así que publicaré lo mismo si ayuda.

$ uname -a
Linux CNPq-Universal-2013 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

$ cat /etc/*-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=14.04
DISTRIB_CODENAME=trusty
DISTRIB_DESCRIPTION="Ubuntu 14.04.1 LTS"
NAME="Ubuntu"
VERSION="14.04.1 LTS, Trusty Tahr"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 14.04.1 LTS"
VERSION_ID="14.04"
HOME_URL="http://www.ubuntu.com/"
SUPPORT_URL="http://help.ubuntu.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"

$lspci -vv
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09) (prog-if 00 [VGA controller])
    Subsystem: Acer Incorporated [ALI] Device 0712
    Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
    Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
    Latency: 0
    Interrupt: pin A routed to IRQ 45
    Region 0: Memory at c2000000 (64-bit, non-prefetchable) [size=4M]
    Region 2: Memory at b0000000 (64-bit, prefetchable) [size=256M]
    Region 4: I/O ports at 3000 [size=64]
    Expansion ROM at <unassigned> [disabled]
    Capabilities: <access denied>
    Kernel driver in use: i915

$ lsmod |grep video
uvcvideo               80885  0 
videobuf2_vmalloc      13216  1 uvcvideo
videobuf2_memops       13362  1 videobuf2_vmalloc
videobuf2_core         40664  1 uvcvideo
videodev              134688  2 uvcvideo,videobuf2_core
video                  19476  2 i915,acer_wmi

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