I met similar issue as well. My monitor is ASUS LS221H which can correctly display outputted from my mobile phone Xperia Neo V via HDMI. From here, we can confirm the monitor and the cable both function well. After powering up, sometimes I could see the logo from BeagleBone Black. Then, what I could see is just no signal reported from the monitor.
I referenced the page, http://circuitco.com/support/index.php?title=BeagleBoneBlack_HDMI, and tried something described in the page via terminal https://192.168.7.2/
Followings are some information of my board.
root@beaglebone:/sys/class/drm/card0/card0-HDMI-A-1# xrandr --verbose
Screen 0: minimum 320 x 200, current 1280 x 720, maximum 2048 x 2048
HDMI-0 connected 1280x720+0+0 (0x42) normal (normal left inverted right x axis y axis) 474mm x 296mm
Identifier: 0x40
Timestamp: 1523547016
Subpixel: unknown
Gamma: 1.0:1.0:1.0
Brightness: 1.0
Clones:
CRTC: 0
CRTCs: 0
Transform: 1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
EDID:
00ffffffffffff000469f12201010101
20130103802f1e782e78f5a655489b26
125054bfef80b30081809500950f9040
714f0101010121399030621a274068b0
3600da281100001c000000ff0039384c
4d56443030343433360a000000fd0038
4b1f5111000a202020202020000000fc
00415355532d4c5332323148ffff01ff
02031e764b909f859484930312010716
230907078301000065030c000000023a
801871382d40582c9600da2811000018
023a80d072382d40102c4580da281100
001e011d8018711c1620582c2500da28
1100009e011d80d0721c1620102c2580
da281100009e011d00bc52d01e20b828
5540da281100001e00000000000000dd
1280x720 (0x41) 74.2MHz +HSync +VSync
h: width 1280 start 1720 end 1760 total 1980 skew 0 clock 37.5KHz
v: height 720 start 725 end 730 total 750 clock 50.0Hz
1280x720 (0x42) 74.2MHz +HSync +VSync *current
h: width 1280 start 1390 end 1430 total 1650 skew 0 clock 45.0KHz
v: height 720 start 725 end 730 total 750 clock 60.0Hz
720x576 (0x43) 27.0MHz -HSync -VSync
h: width 720 start 732 end 796 total 864 skew 0 clock 31.2KHz
v: height 576 start 581 end 586 total 625 clock 50.0Hz
720x480 (0x44) 27.0MHz -HSync -VSync
h: width 720 start 736 end 798 total 858 skew 0 clock 31.5KHz
v: height 480 start 489 end 495 total 525 clock 59.9Hz
640x480 (0x45) 25.2MHz -HSync -VSync
h: width 640 start 656 end 752 total 800 skew 0 clock 31.5KHz
v: height 480 start 490 end 492 total 525 clock 59.9Hz
root@beaglebone:/sys/class/drm/card0/card0-HDMI-A-1# parse-edid edid
parse-edid: parse-edid version 2.0.0
parse-edid: EDID checksum passed.
EDID version 1 revision 3
Section “Monitor”
Block type: 2:0 3:ff
Block type: 2:0 3:fd
Block type: 2:0 3:fc
Identifier “ASUS-LS221Hÿÿ”
VendorName “ACI”
ModelName “ASUS-LS221Hÿÿ”
Block type: 2:0 3:ff
Block type: 2:0 3:fd
HorizSync 31-81
VertRefresh 56-75
Max dot clock (video bandwidth) 170 MHz
Block type: 2:0 3:fc
DPMS capabilities: Active off:yes Suspend:no Standby:no
Mode “1680x1050” # vfreq 59.954Hz, hfreq 65.290kHz
DotClock 146.250000
HTimings 1680 1784 1960 2240
VTimings 1050 1053 1059 1089
Flags “+HSync” “-VSync”
EndMode
Block type: 2:0 3:ff
Block type: 2:0 3:fd
Block type: 2:0 3:fc
EndSection
ID.txt
Cloud9 GNOME Image 2013.06.20
root@beaglebone:~# cat /proc/cmdline
console=ttyO0,115200n8 video=HDMI-A-1::640x480@60 root=/dev/mmcblk0p2 ro rootfstype=ext4 rootwait
Finally, the three steps below work like a charm
root@beaglebone:~# export XAUTHORITY=ls /var/run/gdm/auth-for-root-*/database
root@beaglebone:~# export DISPLAY=:0.0
root@beaglebone:~# xrandr --output HDMI-0 --mode 1280x720 --rate 60
root@beaglebone:/sys/class/drm/card0/card0-HDMI-A-1# fbset
mode “1280x720-0”
D: 0.000 MHz, H: 0.000 kHz, V: 0.000 Hz
geometry 1280 720 1280 720 16
timings 0 0 0 0 0 0 0
accel true
rgba 5/11,6/5,5/0,0/0
endmode
After these, I do see the output on my monitor.
But anyone can tell me, if I tried
optargs=video=HDMI-A-1:1280x720@60 in uEnv.txt
The result is still no signal?
Thanks
honercek