Investigations with modern kms drm drivers.
C
Tried generating an edid-file to "cheat" kms into believing my TV did return such an EDID (it doesn't, but it still supports it). The file is attached to this post.
Added the elements below to /boot/firmware/cmdline.txtAnd /lib/firmware/edid/edid-4k15hz.bin is a file with the EDID for the mode I want. Note the line with DTD 1
Booting with this, gives some progress, but no resolution:
EDID file is loaded, and monitor is percieved as connected. However, the driver doesn't seem satisfied with this resolution and clock (User-defined mode not supported)
So, maybe a dead end. Maybe I'll try against advice above to post a bug-report. I'll consider it or maybe try some more "hacking" first.
C
Tried generating an edid-file to "cheat" kms into believing my TV did return such an EDID (it doesn't, but it still supports it). The file is attached to this post.
Added the elements below to /boot/firmware/cmdline.txt
Code:
video=HDMI-A-1:3840x2160@15D drm.edid_firmware=HDMI-A-1:edid/edid-4k15hz.binCode:
$ edid-decode /lib/firmware/edid/edid-4k15hz.binedid-decode (hex):00 ff ff ff ff ff ff 00 31 d8 00 00 00 00 00 0005 16 01 03 6d 64 38 78 ea 5e c0 a4 59 4a 98 2520 50 54 00 00 00 c1 93 01 01 01 01 01 01 01 0101 01 01 01 01 01 ea 3d 00 f0 f3 70 15 80 78 8035 00 e8 32 32 00 00 1c 00 00 00 ff 00 4c 69 6e75 78 20 23 30 0a 20 20 20 20 00 00 00 fd 00 0e10 1f 21 10 00 0a 20 20 20 20 20 20 00 00 00 fc00 33 38 34 30 78 32 31 36 30 5f 31 35 0a 00 6b----------------Block 0, Base EDID: EDID Structure Version & Revision: 1.3 Vendor & Product Identification: Manufacturer: LNX Model: 0 Made in: week 5 of 2012 Basic Display Parameters & Features: Analog display Signal Level Standard: 0.700 : 0.000 : 0.700 V p-p Blank level equals black level Sync: Separate Composite Serration Maximum image size: 100 cm x 56 cm Gamma: 2.20 DPMS levels: Standby Suspend Off RGB color display First detailed timing is the preferred timing Color Characteristics: Red : 0.6416, 0.3486 Green: 0.2919, 0.5957 Blue : 0.1474, 0.1250 White: 0.3125, 0.3281 Established Timings I & II: none Standard Timings: GTF : 1792x1433 78.999907 Hz 5:4 118.421 kHz 291.789000 MHz Detailed Timing Descriptors: DTD 1: 3840x2160 14.990323 Hz 16:9 32.694 kHz 158.500000 MHz (1000 mm x 562 mm) Hfront 120 Hsync 128 Hback 760 Hpol N Vfront 3 Vsync 5 Vback 13 Vpol P Display Product Serial Number: 'Linux #0' Display Range Limits: Monitor ranges (GTF): 14-16 Hz V, 31-33 kHz H, max dotclock 160 MHz Display Product Name: '3840x2160_15'Checksum: 0x6bCode:
$ cat /sys/class/drm/card0-HDMI-A-1/edid | hexdump -C | head -2000000000 00 ff ff ff ff ff ff 00 31 d8 00 00 00 00 00 00 |........1.......|00000010 05 16 01 03 6d 64 38 78 ea 5e c0 a4 59 4a 98 25 |....md8x.^..YJ.%|00000020 20 50 54 00 00 00 c1 93 01 01 01 01 01 01 01 01 | PT.............|00000030 01 01 01 01 01 01 ea 3d 00 f0 f3 70 15 80 78 80 |.......=...p..x.|00000040 35 00 e8 32 32 00 00 1c 00 00 00 ff 00 4c 69 6e |5..22........Lin|00000050 75 78 20 23 30 0a 20 20 20 20 00 00 00 fd 00 0e |ux #0. ......|00000060 10 1f 21 10 00 0a 20 20 20 20 20 20 00 00 00 fc |..!... ....|00000070 00 33 38 34 30 78 32 31 36 30 5f 31 35 0a 00 6b |.3840x2160_15..k|00000080$ cat /sys/class/drm/card0-HDMI-A-1/statusconnectedCode:
$ dmesg | grep -i \\[drm\\][ 11.716128] [drm] forcing HDMI-A-1 connector on[ 11.804082] [drm] Initialized vc4 0.0.0 for soc:gpu on minor 0[ 11.847737] vc4-drm soc:gpu: [drm] User-defined mode not supported: "3840x2160": 15 158500 3840 3960 4088 4848 2160 2163 2168 2181 0x68 0x6[ 11.847805] vc4-drm soc:gpu: [drm] Cannot find any crtc or sizes[ 11.848611] vc4-drm soc:gpu: [drm] User-defined mode not supported: "3840x2160": 15 158500 3840 3960 4088 4848 2160 2163 2168 2181 0x68 0x6[ 11.848676] vc4-drm soc:gpu: [drm] Cannot find any crtc or sizesStatistics: Posted by grasdk — Fri May 30, 2025 10:14 pm