於是藉著

edidparser edid.dat

Enabling fuzzy format match…
Parsing edid.dat…
HDMI:EDID version 1.4, 0 extensions, screen size 22×14 cm
HDMI:EDID features – videodef 0x90 !standby !suspend !active off; colour encoding:RGB444; sRGB is not default colourspace; preferred format is native; support discrete frame rate
HDMI:EDID found monitor ascii descriptor tag 0xfe
HDMI:EDID ignored unknown descriptor tag 0x0
HDMI:EDID does not yet know monitor vertical range, setting to default 24 to 120Hz
HDMI:EDID failed to find a matching detail format for 1280x800p hfp:64 hs:48 hbp:124 vfp:5 vs:7 vbp:12 pixel clock:75 MHz
HDMI:EDID calculated refresh rate is 60 Hz
HDMI:EDID guessing the format to be 1280x800p @60 Hz
HDMI:EDID found preferred DMT detail timing format: 1280x800p @ 60 Hz (27)
HDMI:EDID failed to find a matching detail format for 1280x800p hfp:1023 hs:1023 hbp:-1918 vfp:63 vs:63 vbp:-104 pixel clock:46 MHz
HDMI:EDID calculated refresh rate is 40 Hz
HDMI:EDID guessing the format to be 1280x800p @30 Hz
HDMI:EDID found unknown detail timing format: 1280x800p hfp:1023 hs:1023 hbp:-1918 vfp:63 vs:63 vbp:-104 pixel clock:46 MHz
HDMI:EDID established timing I/II bytes are 00 00 00
HDMI:EDID standard timings block x 8: 0x0101 0101 0101 0101 0101 0101 0101 0101
HDMI:EDID adding mandatory support for DMT (4) 640x480p @ 60Hz
HDMI:EDID filtering formats with pixel clock > 162 MHz or h. blanking > 1023
HDMI:EDID best score mode initialised to DMT (4) 640x480p @ 60 Hz with pixel clock 25 MHz (score 0)
HDMI:EDID best score mode is now DMT (4) 640x480p @ 60 Hz with pixel clock 25 MHz (score 36864)
HDMI:EDID best score mode is now DMT (27) 1280x800p @ 60 Hz with pixel clock 71 MHz (score 5184320)
HDMI:EDID preferred mode remained as DMT (27) 1280x800p @ 60 Hz with pixel clock 71 MHz
HDMI:EDID has only DVI support and no audio support
edid_parser exited with code 0

 

以及

edid-decode edid.dat

Extracted contents:
header: 00 ff ff ff ff ff ff 00
serial number: 30 e4 45 03 00 00 00 00 00 15
version: 01 04
basic params: 90 16 0e 78 02
chroma info: e8 87 96 5a 55 95 28 22 51 55
established: 00 00 00
standard: 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01
descriptor 1: 4c 1d 00 ec 50 20 18 30 40 30 57 00 d9 88 00 00 00 1b
descriptor 2: 16 12 00 80 50 20 16 30 ff ff ff ff ff ff ff ff 00 1b
descriptor 3: 00 00 00 fe 00 43 33 47 52 4e 80 31 30 31 57 58 31 0a
descriptor 4: 00 00 00 00 00 00 41 32 a8 00 00 00 00 01 01 0a 20 20
extensions: 00
checksum: 9a

Manufacturer: LGD Model 345 Serial Number 0
Made week 0 of 2011
EDID version: 1.4
Digital display
6 bits per primary color channel
Digital interface is not defined
Maximum image size: 22 cm x 14 cm
Gamma: 2.20
Supported color formats: RGB 4:4:4
First detailed timing is preferred timing
Established timings supported:
Standard timings supported:
Detailed mode: Clock 75.000 MHz, 217 mm x 136 mm
1280 1344 1392 1516 hborder 0
800 805 812 824 vborder 0
+hsync -vsync
Detailed mode: Clock 46.300 MHz, 4095 mm x 4095 mm
1280 2303 3326 1408 hborder 255
800 863 926 822 vborder 0
+hsync -vsync
ASCII string: C3GRN
Manufacturer-specified data, tag 0
Checksum: 0x9a (valid)
EDID block does NOT conform to EDID 1.3!
Missing name descriptor
Missing monitor ranges
Detailed block string not properly terminated

 

拼湊出產生了這個測試模式︰

hdmi_timings=1280 1 64 48 124 800 0 5 7 12 0 0 1 60 0 75000000 5

 

且依據

‧Specifying hdmi_group=1 in config.txt prevents later use of hdmi_timings #792

‧Please can the ability to modify HDMI timings on the fly (i.e. without having to carry out a reboot) be added to the firmware drivers #637

 

文本的精神，復作動態之驗證︰

pi@raspberrypi:~  tvservice -e "DMT 87"
Powering on HDMI with explicit settings (DMT mode 87)
pi@raspberrypi:~  vcgencmd measure_clock pixel
frequency(29)=75000000
pi@raspberrypi:~ $

 

因黑屏事件，偶而發現在 X Window 系統中，需要

Ctrl + Alt + F1 ；

Ctrl + Alt + F7 。

重啟該顯示器也。

方法既已知，其餘者或不必多講的吧◎