panel-probe.txt

[   0.000] --- capture start, waiting for /dev/ttyACM0 ---
[   0.098] --- port opened ---
␛[!p␛]104␛\␛[0m␛[?7h␛[1G␛[0J␛7␛[32766;32766H␛[6n␛8␛[!p␛]104␛\␛[0m␛[?7h␛[1G␛[0J␛7␛[32766;32766H␛[6n␛8␛]3008;start=2881e61ff3ed47a2854d54fafa3279c0;user=root;hostname=nixos;machineid=5232f89e0de34dfda0403ae9b5f50e1e;bootid=397efb4217924f14a39788f5a1b3d5a8;pid=653;comm=(agetty);servicename=serial-getty@ttyS0.service;invocationid=e3455a581bfe455cbd8e5e62b9848c92;type=service␛\␛P+q6E616D65␛\


␛[1;32m<<< Welcome to NixOS 26.11.20260919.20b1ddd (riscv64) - ttyS0 >>>␛[0m


nixos login: root (automatic login)


␛]3008;start=019563a81ca6408887fab1053c0f4481;user=root;hostname=nixos;machineid=5232f89e0de34dfda0403ae9b5f50e1e;bootid=397efb4217924f14a39788f5a1b3d5a8;pid=653;comm=login;targetuser=root;sessionid=2;type=session␛\␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m [  11.712] --- sending: dmesg | grep -iE "drm|dsi|panel|canaan|vo@|backlight" | head -40 ---
dmesg | grep -iE "drm|dsi|panel|canaan|vo@|backlight" | head -40 
␛[A␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[C␛[K0
␛[?2004l
[    0.160265] platform 90840000.vo: Fixed dependency cycle(s) with /soc/dsi@90850000
[    0.160426] platform 90840000.vo: Fixed dependency cycle(s) with /soc/dsi@90850000
[    0.160524] platform 90850000.dsi: Fixed dependency cycle(s) with /soc/dsi@90850000/panel@0
[    0.160541] platform 90850000.dsi: Fixed dependency cycle(s) with /soc/vo@90840000
[    0.655048] canaan-vo 90840000.vo: probe
[    0.655930] canaan-mipi-dsi 90850000.dsi: Fixed dependency cycle(s) with /soc/dsi@90850000/panel@0
[    0.656030] mipi-dsi 90850000.dsi.0: Fixed dependency cycle(s) with /soc/dsi@90850000
[    1.077819] canaan-mipi-dsi 90850000.dsi: Attached device universal
[    1.079739] canaan-vo 90840000.vo: background color is ffffff
[    1.079985] canaan-drm soc:display-subsystem: bound 90840000.vo (ops 0xffffffff83696b48)
[    1.080043] canaan-drm soc:display-subsystem: bound 90850000.dsi (ops 0xffffffff83696fe0)
[    1.081107] [drm] Initialized canaan-drm 1.0.0 20230501 for soc:display-subsystem on minor 0
[    1.084175] canaan-drm soc:display-subsystem: [drm] bpp/depth value of 32/24 not supported
[    1.084194] canaan-drm soc:display-subsystem: [drm] No compatible format found
[    1.093970] canaan-drm soc:display-subsystem: [drm] *ERROR* fbdev: Failed to setup generic emulation (ret=-22)
[    1.104083] canaan-drm soc:display-subsystem: [drm:canaan_drm_bind] Canaan K230 DRM driver register successfully
[    1.109246] canaan-drm soc:display-subsystem: [drm] bpp/depth value of 32/24 not supported
[    1.109265] canaan-drm soc:display-subsystem: [drm] No compatible format found
[    1.112542] canaan-drm soc:display-subsystem: [drm] *ERROR* fbdev: Failed to setup generic emulation (ret=-22)
[   22.947804] systemd[1]: Load Kernel Module drm skipped, unmet condition check ConditionKernelModuleLoaded=!drm
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m 
␛[?2004l
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m [  12.115] --- sending: ls -l /dev/dri/ 2>&1; ls -l /dev/fb* 2>&1 ---
ls -l /dev/dri/ 2>&1; ls -l /dev/fb* 2>&1
␛[?2004l
total 0
drwxr-xr-x 2 root root      60 Mar 17 19:56 ␛[0m␛[01;34mby-path␛[0m
crw-rw---- 1 root video 226, 0 Mar 17 19:56 ␛[40;33;01mcard0␛[0m
ls: cannot access '/dev/fb*': No such file or directory
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m 
␛[?2004l
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m [  12.316] --- sending: fbset -i 2>&1 | head -20 ---
fbset -i 2>&1 | head -20
␛[?2004l
open /dev/fb0: No such file or directory
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m 
␛[?2004l
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m [  12.516] --- sending: modetest -M canaan-drm -c 2>&1 | head -30 ---
modetest -M canaan-drm -c 2>&1 | head -30
␛[?2004l
opened device `Canaan K230 DRM driver` on driver `canaan-drm` (version 1.0.0 at 20230501)
Connectors:
id	encoder	status		name		size (mm)	modes	encoders
48	0	connected	DSI-1          	44x95		1	47
  modes:
	index name refresh (Hz) hdisp hss hse htot vdisp vss vse vtot
  #0 568x1232 39.63 568 608 648 788 1232 1248 1252 1268 39600 flags: ; type: preferred, driver
  props:
	1 EDID:
		flags: immutable blob
		blobs:

		value:
	2 DPMS:
		flags: enum
		enums: On=0 Standby=1 Suspend=2 Off=3
		value: 0
	5 link-status:
		flags: enum
		enums: Good=0 Bad=1
		value: 0
	6 non-desktop:
		flags: immutable range
		values: 0 1
		value: 0
	4 TILE:
		flags: immutable blob
		blobs:

		value:
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m 
␛[?2004l
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m [  12.717] --- sending: for z in /sys/class/thermal/thermal_zone*; do echo "$z $(cat $z/type) $(cat $z/temp)"; done 2>&1 ---
for z in /sys/class/thermal/thermal_zone*; do echo "$z $(cat $z/type) $(cat $z/temp)"; done 2>&1
␛[?2004l
/sys/class/thermal/thermal_zone0 canaan_thermal_zone 7179
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m 
␛[?2004l
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m [  12.922] --- sending: cat /sys/class/thermal/thermal_zone0/trip_point_* 2>&1 | head ---
cat /sys/class/thermal/thermal_zone0/trip_point_* 2>&1 | head
␛[?2004l
cat: '/sys/class/thermal/thermal_zone0/trip_point_*': No such file or directory
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m 
␛[?2004l
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m [  13.123] --- sending: dmesg | grep -iE "goodix|berlin|touch|i2c" | head -20 ---
dmesg | grep -iE "goodix|berlin|touch|i2c" | head -20
␛[?2004l
[    1.495480] goodix-berlin-i2c 1-005d: supply avdd not found, using dummy regulator
[    1.495631] goodix-berlin-i2c 1-005d: supply iovdd not found, using dummy regulator
[    1.652309] input: Goodix Berlin Capacitive TouchScreen as /devices/platform/soc/91408000.i2c/i2c-1/1-005d/input/input0
[    1.653960] i2c_dev: i2c /dev entries driver
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m 
␛[?2004l
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m [  13.323] --- sending: i2cdetect -y -r 3 2>&1 | head -12 ---
i2cdetect -y -r 3 2>&1 | head -12
␛[?2004l
Error: Could not open file `/dev/i2c-3' or `/dev/i2c/3': No such file or directory
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m 
␛[?2004l
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m [  13.523] --- sending: ls -l /dev/input/ 2>&1; cat /proc/bus/input/devices 2>&1 | head -30 ---
ls -l /dev/input/ 2>&1; cat /proc/bus/input/devices 2>&1 | head -30
␛[?2004l
total 0
drwxr-xr-x 2 root root      60 Mar 17 19:56 ␛[0m␛[01;34mby-path␛[0m
crw-rw---- 1 root input 13, 64 Mar 17 19:56 ␛[40;33;01mevent0␛[0m
crw-rw---- 1 root input 13, 63 Mar 17 19:56 ␛[40;33;01mmice␛[0m
crw-rw---- 1 root input 13, 32 Mar 17 19:56 ␛[40;33;01mmouse0␛[0m
I: Bus=0018 Vendor=0000 Product=0000 Version=0000
N: Name="Goodix Berlin Capacitive TouchScreen"
P: Phys=input/ts
S: Sysfs=/devices/platform/soc/91408000.i2c/i2c-1/1-005d/input/input0
U: Uniq=
H: Handlers=mouse0 event0 
B: PROP=2
B: EV=b
B: KEY=400 0 0 0 0 0
B: ABS=261800000000003

␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m 
␛[?2004l
␛[?2004h

␛[1;31m[␛]0;root@nixos: ~␇root@nixos:~]#␛[0m [ 120.058] --- capture end ---


=====================================================================
2026-09-21: /dev/fb0 exists at 568x1232 (display/panel task 3.1)
=====================================================================

Captured on hardware over the CH342 console, after three fixes landed:
the 16 bpp fbdev format fix, the bounded DSI PHY wait, and the
ModemManager udev rule that stopped a host daemon corrupting the console.

    [root@nixos:~]# fbset -i
    mode "568x1232"
        geometry 568 1232 568 1232 16
        timings 0 0 0 0 0 0 0
        rgba 5/11,6/5,5/0,0/0
    endmode

    Frame buffer device information:
        Name        : canaan-drmdrmfb
        Size        : 1400832
        Type        : PACKED PIXELS
        Visual      : TRUECOLOR

    [root@nixos:~]# cat /sys/class/graphics/fb0/virtual_size
    568,1232
    [root@nixos:~]# cat /sys/class/graphics/fb0/bits_per_pixel
    16

    [root@nixos:~]# ls -l /dev/fb* /dev/dri/
    crw-rw---- 1 root video  29, 0 /dev/fb0
    crw-rw---- 1 root video 226, 0 /dev/dri/card0

rgba 5/11,6/5,5/0 is RGB565, which is the point of the fbdev change:
canaan_drv.c asked drm_fbdev_generic_setup() for 32 bpp (XRGB8888) and the
driver's RGB planes advertise AR24 AR12 AR15 RG24 RG16 BG24 -- no XR24 --
so format negotiation failed and no framebuffer was created at all.

WHAT THIS DOES NOT SHOW

The framebuffer exists; the glass is still dark. The DSI block reads back
as 0xffffffff and every DCS write to the panel times out:

    canaan-mipi-dsi 90850000.dsi: PHY_STATUS 0xffffffff != 0x1fbd after 2001 tries, continuing
    canaan-mipi-dsi 90850000.dsi: failed to get available write payload FIFO
    canaan-panel-dsi 90850000.dsi.0: failed to write dcs cmd: -110

All-ones reads plus write timeouts are an unpowered block, not a
misconfigured one. See docs/evidence/dsi-phy-hang.md. Task 3.2 asks for a
photograph precisely because a framebuffer node is not evidence that
anything is visible, and this is exactly that case.