Comment 97 for bug 1860284

Thanks for the great work!

Hotplugging thunderbolt docks definitely work better, but I still have a couple issues.

Before I start, here is some info about my setup.

I use KDE on Arch Linux, but it shouldn't affect the problem. uname -a prints:
Linux MyPC 6.1.1-arch1-1 #1 SMP PREEMPT_DYNAMIC Wed, 21 Dec 2022 22:27:55 +0000 x86_64 GNU/Linux

Regarding BIOS, I am running the non-standard Lenovo C940 BIOS that some Lenovo engineer temporarily released on their forum to fix the speakers on Linux (version AUCN57WW).

My dock is a "Kensington SD5500T/SD5550T Thunderbolt 3 and USB-C Docking Station".

But now to the issues.

First: The fix currently mainlined in the kernel doesn't work for me. After comparing the file arch/x86/pci/acpi.c on github with the result of dmidecode (see below), I think it the check for DMI_PRODUCT_VERSION should be changed to checking the product family. It could potentially be related to my non-standard BIOS version, but I can't check that.

Second: Since the current fix didn't apply to my computer, I tried compiling the kernel myself and applying the patch from comment #62.
My dock has both a USB hub and display outputs, and on the non-patched kernel, if I tried hotplugging it, the USB hub didn't work, but the external displays always did (and sometimes the computer crashed).
On the patched kernel, if I hotplug, the USB hub always works, and I haven't experienced any crashes, but the external displays aren't recognized. More specifically, if the dock is unplugged when booting and I then hotplug it, they aren't recognized. If instead the computer is docked while booting, the displays work, and if I unplug the dock and then replug it within ~5-10 seconds, the displays are recognized again. If I instead have the dock unplugged for a minute or so, the displays are not recognized when replugging the dock.
I have tried running lspci -vv, and the output differs between if the computer was docked on boot and after it was un- and replugged, but it doesn't differ between if the external displays are recognized or not.

I would attach dmesg and lspci -xxxx, but I cannot figure out how to create attachments, so please help me if you need that info. And please specify under which conditions you want the logs. :)

--- dmidecode ---
Handle 0x0001, DMI type 1, 27 bytes
System Information
        Manufacturer: LENOVO
        Product Name: 81Q9
        Version: Yoga C940
        Serial Number: [...]
        UUID: [...]
        Wake-up Type: Power Switch
        SKU Number: LENOVO_MT_81Q9_BU_idea_FM_Yoga C940-14IIL
        Family: Yoga C940-14IIL