[BUG] AMD Ryzen 7 4700H Renoir: brightness + external screen do not work

[Koos Pol]

Hello,

[I posted this email yesterday to this mailinglist without being 
subscribed. Some of you may have received this email already yesterday.]

I'm running into a kernel problem on openSUSE. After investigation and 
various tests, the openSUSE kernel maintainer determined it's an 
upstream kernel issue, which I should report upstream. I believe this 
mailing list should be the correct starting point for my bug report. 
Please correct me if this is not the case.

The original bug report can be found here: 
https://bugzilla.opensuse.org/show_bug.cgi?id=1186896

=== Summary===
I don't have brightness control or an external screen, without disabling 
acpi.
If I disable acpi (kernel boot option "acpi=off") than I do have 
brightness control, and the external screen works too. But obviously I 
then don't have any acpi functionality (single core, no Fn keys, etc)

===Details===
Laptop: Clevo NL51RU
BIOS: insyde 1.07.05

Distribution:
openSUSE Leap 15.2/15.3 + Tumbleweed

Recent kernels tried (from the openSUSE repos):
kernel-default-5.12.12
kernel-default-5.13.rc7

CPU: Rhyzen 7 4700U
Graphics:
# lspci -nnk | grep -A3 VGA
05:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. 
[AMD/ATI] Renoir [1002:1636] (rev c2)
         Subsystem: CLEVO/KAPOK Computer Device [1558:a500]


Detailed symptoms:

*Boot option**
* 	*Boots?**
* 	*Brightness?**
* 	*Notes**
*
-
	No
	
	Hangs at "switching to amdgpudrmfb from EFI VGA" [*]
nomodeset
	Yes
	No
	Any attempt to set the brightness results in a pop-up of the external 
monitor widget [**]
amdgpu.backlight=0
	No
	
	Hangs at "switching to amdgpudrmfb from EFI VGA" [*]
amdgpu.backlight=0 nomodeset
	Yes
	No
	
acpi=off
	Yes
	Yes
	No acpi functionality


[*]
For ease of reference: these are the last 4 lines from the boot log if 
the laptop hangs:
     [drm] amdgpu kernel modesetting enabled.
     Virtual CRAT table created for CPU
     amdgpu: Topology: Add CPU node
     fb0: switching to amdgpudrmfb from EFI VGA

[**]
For those two scenarios above where the laptop boots fine, but without 
brightness control, there is this funny additional symptom:
Turning the scroll wheel over de battery icon in the system tray doesn't 
do anything. No change in brightness. But I do get the immediate and 
unexplainable popup of the external monitor widget (see attachment).

Peculiarly, the settings are correctly registered.

rietgors:# cd 
/sys/devices/pci0000:00/0000:00:08.1/0000:05:00.0/backlight/acpi_video0

Before:
rietgors:# cat actual_brightness max_brightness
21
49

After:
rietgors:# cat actual_brightness max_brightness
36
49

Oddly, the max_brightness value is 49. But in the scenario where I *do* 
have brightness control (acpi=off), the max_brightness is 255.

Exactly the same happens when I directly echo values in the "brightness" 
device from the command line. No change in brightness but an immediate 
popup of the external monitor widget.


Please be aware: I think I'm computer savvy, but working with or on the 
kernel is way out of my comfort zone. I'd be happy to investigate and 
try further. But I probably will need detailed instructions.

Thanks,
Koos

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/amd-gfx/attachments/20210627/59ddc240/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ext_screen_widget.png
Type: image/png
Size: 84397 bytes
Desc: not available
URL: <https://lists.freedesktop.org/archives/amd-gfx/attachments/20210627/59ddc240/attachment-0001.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: boot_log.jpg
Type: image/jpeg
Size: 602351 bytes
Desc: not available
URL: <https://lists.freedesktop.org/archives/amd-gfx/attachments/20210627/59ddc240/attachment-0001.jpg>