pi4(4GB) work in headless and disable_fw_kms_setup=1,but Xorg.0.log still show (II) modeset(0): Output HDMI-1 connected

Start by comparing /boot/config.txt, /proc/cmdline, and /var/log/Xorg.0.log between the Pi 4 4GB and 8GB headless setups, focusing on hdmi_force_hotplug, disable_fw_kms_setup, and the video=HDMI-A-1 setting. Reproduce the configuration and verify that headless HDMI detection, page-flip errors, and the VNC resolution behave correctly without a monitor.

I have a pi4 (4GB) running the latest 2023-02-21-raspios-bullseye-arm64 with a recent kernel upgrade to 6.1.19-v8+
uname -a
Linux raspberrypi4 6.1.19-v8+ #1637 SMP PREEMPT Tue Mar 14 11:11:47 GMT 2023 aarch64 GNU/Linux
Part of /boot/config.txt
#hdmi_force_hotplug=1
hdmi_group=2
hdmi_mode=82
dtoverlay=vc4-kms-v3d
cat /proc/cmdline
coherent_pool=1M 8250.nr_uarts=0 snd_bcm2835.enable_headphones=0 snd_bcm2835.enable_headphones=1 snd_bcm2835.enable_hdmi=1 snd_bcm2835.enable_hdmi=0 video=HDMI-A-1:1920x1080M@60 smsc95xx.macaddr=DC:A6:32:30:9A:CA vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000 boot=overlay console=ttyS0,115200 console=tty1 root=PARTUUID=1cad5af1-02 rootfstype=ext4 fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles

Recently I noticed that /var/log/Xorg.0.log keeps coming up
[ 400.962] (WW) modeset(0): flip queue failed: Device or resource busy
[ 400.962] (WW) modeset(0): Page flip failed: Device or resource busy
[ 400.962] (EE) modeset(0): present flip failed
[ 401.067] (WW) modeset(0): flip queue failed: Device or resource busy
[ 401.067] (WW) modeset(0): Page flip failed: Device or resource busy
[ 401.067] (EE) modeset(0): present flip failed
[ 402.573] (WW) modeset(0): flip queue failed: Device or resource busy
[ 402.573] (WW) modeset(0): Page flip failed: Device or resource busy
[ 402.573] (EE) modeset(0): present flip failed
[ 403.961] (WW) modeset(0): flip queue failed: Device or resource busy
[ 403.961] (WW) modeset(0): Page flip failed: Device or resource busy
[ 403.962] (EE) modeset(0): present flip failed
[ 404.069] (WW) modeset(0): flip queue failed: Device or resource busy
[ 404.069] (WW) modeset(0): Page flip failed: Device or resource busy
[ 404.069] (EE) modeset(0): present flip failed
It is suspected that it is related to the kernel upgrade to 6.1.19-v8+. If the monitor is connected, the above log will not be generated.
problem
1.headless and #hdmi_force_hotplug=1, which should not detect hdmi, but /var/log/Xorg.0.log always shows (II) modeset(0): Output HDMI-1 connected,and cmdline has video= HDMIA-1 :1920x1080M@60
2.In /boot/config.txt, set disable_fw_kms_setup=1, cmdline no longer has video=HDMI-A-1:1920x1080M@60, Xorg.0.log no longer generates Page flip failed log, But Xorg.0.log still shows (II) modeset(0): Output HDMI-1 connected, and because hdmi show connected, the vnc resolution does not work.

cat /etc/xdg/autostart/vnc_xrandr.desktop
[Desktop Entry]
Type=Application
Name=vnc_xrandr
Comment=Set resolution for VNC
NoDisplay=true
Exec=sh -c "if ! (xrandr | grep -q -w connected) ; then /usr/bin/xrandr --fb 1920x1080 ; fi"

When I put the sd card of pi4 (4GB) on another pi4 (8GB) and ran it headless, the resolution of vnc did not have the above problem, as follows:
1.If #hdmi_force_hotplug=1 or disable_fw_kms_setup=1, Then cmdline does not have video=HDMI-A-1:1920x1080M@60,Xorg.0.log shows (II) modeset(0): output HDMI-1 has been disconnected, vnc resolution is 1920x1080
2.if hdmi_force_hotplug=1 and #disable_fw_kms_setup=1, cmdline has video=HDMI-A-1:1920x1080M@60D, Xorg.0.log shows (II) modeset(0): Output HDMI-1 connected, vnc resolution is 1920x1080, but Xorg.0.log will keep generating Page flip failed log.

There is one more difference between pi4 (4GB) and pi4 (8GB) regarding the hdmi_force_hotplug parameter
pi4 (4GB) (disable_fw_kms_setup=1), if #hdmi_force_hotplug=1, cmdline has video=HDMI-A-1:1920x1080M@60. if hdmi_force_hotplug=1, cmdline has video=HDMI-A-1:1920x1080M@60D.
pi4 (8GB) (disable_fw_kms_setup=1), if #hdmi_force_hotplug=1, cmdline does not have video=HDMI-A-1:1920x1080M@60. if hdmi_force_hotplug=1, cmdline has video=HDMI-A-1:1920x1080M@60D.