5.7-rc1 kernel, DDC/CI monitor control not working

The following commit between kernel 5.6 and 5.7-rc1 breaks DDC/CI control of the monitor for me:

drm/amdgpu/display: split dp connector registration (v4):
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=405a1f9090d1acec75aeb86569da60beca9fe68f

405a1f9090d1acec75aeb86569da60beca9fe68f

I found this commit through doing 'git bisect' between v5.7-rc1 (bad) and v5.6 (good) tags.

My hardware setup is an AMD RX480 card and the monitor is connected through Displayport on output DP-1 (DisplayPort-0 in Xorg):

$ grep . /sys/class/drm/card0/card0-*/status
/sys/class/drm/card0/card0-DP-1/status:connected
/sys/class/drm/card0/card0-DP-2/status:disconnected
/sys/class/drm/card0/card0-DVI-D-1/status:disconnected
/sys/class/drm/card0/card0-HDMI-A-1/status:disconnected
/sys/class/drm/card0/card0-HDMI-A-2/status:disconnected

Here's the "ddcutil" and "i2cdetect" output on a good kernel:

$ sudo ddcutil detect
Display 1
I2C bus:             /dev/i2c-1
EDID synopsis:
    Mfg id:           ACR
    Model:            XF270HU
    Serial number:    T78EE0048521
    Manufacture year: 2018
    EDID version:     1.4
VCP version:         2.2

$ sudo i2cdetect -l
i2c-3	i2c       	dmdc                            	I2C adapter
i2c-1	i2c       	dmdc                            	I2C adapter
i2c-8	smbus     	SMBus PIIX4 adapter port 2 at 0b00	SMBus adapter
i2c-6	i2c       	AMDGPU DM i2c hw bus 4          	I2C adapter
i2c-4	i2c       	AMDGPU DM i2c hw bus 2          	I2C adapter
i2c-2	i2c       	AMDGPU DM i2c hw bus 1          	I2C adapter
i2c-0	i2c       	AMDGPU DM i2c hw bus 0          	I2C adapter
i2c-7	smbus     	SMBus PIIX4 adapter port 0 at 0b00	SMBus adapter
i2c-5	i2c       	AMDGPU DM i2c hw bus 3          	I2C adapter

On a bad kernel, things look like this:

$ sudo ddcutil detect
No displays found

$ sudo i2cdetect -l
i2c-3	i2c       	AMDGPU DM i2c hw bus 3          	I2C adapter
i2c-1	i2c       	AMDGPU DM i2c hw bus 1          	I2C adapter
i2c-6	smbus     	SMBus PIIX4 adapter port 2 at 0b00	SMBus adapter
i2c-4	i2c       	AMDGPU DM i2c hw bus 4          	I2C adapter
i2c-2	i2c       	AMDGPU DM i2c hw bus 2          	I2C adapter
i2c-0	i2c       	AMDGPU DM i2c hw bus 0          	I2C adapter
i2c-5	smbus     	SMBus PIIX4 adapter port 0 at 0b00	SMBus adapter

EDIT:

Here's the Xorg log and dmesg output for good 5.6.4 kernel and bad 5.7-rc1:

good-5.6.4_Xorg.0.log

bad-5.7.0-rc1_Xorg.0.log

good-5.6.4_dmesg.txt

bad-5.7.0-rc1_dmesg.txt