[Nouveau] Optimus HDMI hotplug fails with "DRM: Dropped ACPI reprobe event due to RPM error: -22"

[Craig Ringer]

On Thu, 18 Feb 2021 at 11:06, Craig Ringer <ringerc at ringerc.id.au> wrote:

> Hi all
>
> I'm trying to get HDMI hotplug working on my Lenovo T15g laptop with
> Optimus graphics. HDMI works when plugged in at boot, but does not work
> when hotplugged after boot, or when hot-unplugged then re-plugged. The
> external display is not detected, its status remains 'disconnected' in
> sysfs, and the display stays in what looks like DPMS-off state.
> [snip]
> I'll attach a detailed lspci, bigger excerpts from demesg, etc in a
> followup to make sure I don't upset any mail filter.
>

Detailed PCI info and trimmed dmesg uploaded to a GDrive since I don't
really want to send all that to the whole list. Files here:

https://drive.google.com/drive/folders/1oE3ow7d8N6npDNbL8vqHYjbAvvJCUcPN?usp=sharing

Contains:

$ sudo lspci -vvvvnnnnPPq | sed '/Device Serial Number/d' > pci.list

$ sudo dmesg | egrep -v
'e1000e|nvme|BTRFS|audit:|SELinux:|systemd\[1\]|thunderbolt|cfg80211|WiFi|Bluetooth|battery|iwlwifi|uvcvideo|usbcore|zram|iTCO_wdt|snd_hda_intel|squashfs|EXT4-fs|iSCSI|wlp0s20f3|IPv6|\<bridge\>|\<tun\>|virbr0|rfkill|nf_conntrack|psmouse'
| sed 's/SerialNumber.*$/SerialNumber REDACTED/' > dmesg.out

$ sudo dmidecode | sed '/Serial Number:/d;/Asset Tag/d' > dmi.dump

$ sudo cat /sys/kernel/debug/vgaswitcheroo/switch
0:DIS: :DynOff:0000:01:00.0
1:IGD:+:Pwr:0000:00:02.0
2:DIS-Audio: :DynOff:0000:01:00.1

I can provide raw or decompiled ACPI DSDT and SSDTs on request, as well as
kernel logs with higher log levels, a nouveau module debug string, info
from /sys/kernel/debug, 'perf' runs, etc.

There's also some nouveau info in /sys/kernel/debug/dri/1 .

Also, I note that

    echo 'on' > /sys/kernel/debug/dri/1/HDMI-A-1/force

does not appear to have any effect when the display is plugged in and
turned on, but not being detected by nouveau. Also true for other ports
DP-1, DP-2, DP-3, eDP-2.

-- 
Craig Ringer
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