No brightness control in windows 10 VM guest while passthrough igpu from proxmox-ve.

[a85551]

laptop i7 7500U HD 620

PVE 7.1

passthrough worked in guest, with windows graphic driver installed fine, but display with max brightness, there is no brightness control in windows display control pannel.

GPU-Z in VM guest:

[JosueO_Intel]

Hello a85551,

Thank you for posting on the Intel®️ communities. In order to have a better understanding of the issue, please share with us the following information: 

1. Does the issue also occur on the host computer?
2. Intel® SSU report of the host computer.
   1. https://downloadcenter.intel.com/download/25293/Intel-System-Support-Utility-for-Windows- 
   2. Open the application and select "Everything" click on "Scan" to see the system and device information. By default, Intel®️ SSU will take you to the "Summary View". Click on the menu where it says "Summary" to change to "Detailed View".  
   3. Click on "Next", save the report and attach it to your response.

Regards, 

Josue O.  

Intel Customer Support Technician

[a85551]

Thanks for your reply!

1. No, no issue in the host. If I install windows 10 as host OS,  I can adjust brightness with slider bar.

When the same PVE as host, and Install debian with GNOME as guest, I also can adjust brightness in debian.

2. ok, SSU results in the attachment. (a few chinese words in the text file)

[JosueO_Intel]

Hello a85551,

We recommend performing a clean install of the latest graphics drivers provided by the system manufacturer since these drivers are customized. Follow these steps:

Check Windows* updates:

• Click the Windows Start button. 

• Click the search and type Windows updates and click on that option.

• Select Check for Updates and ensure you have the latest Windows* version. 

Clean installation of the Graphics Driver:

1- Download the latest customized driver from the Computer Manufacturer Support Websites and save the installer on the computer.

2- Disconnect from the internet to make sure the driver will not be automatically updated by Windows.

3- Uninstall the Intel Graphics driver. To do this, please follow the steps on the link below under these sections:

• Uninstalling the Intel Graphics Driver via the Device Manager Method

https://www.intel.com/content/www/us/en/support/articles/000005598/graphics.html

4- Restart the computer.

5- Right-click the Windows Start button. Select Device Manager.

6- If no older drivers are stored in the system, the graphics controller in Device Manager should now be listed as 'Microsoft Basic Display Adapter', 'Standard VGA Graphics Adapter', or similar. If not, repeat step 3. Repeat the process until it is listed as 'Microsoft Basic Display Adapter'.

7- Install the latest graphics driver provided by the system manufacturer.

8- Once the latest driver has been installed, enable the internet connection again.

If the issue persists, repeat the Clean installation process using the latest Intel® generic graphics driver available at Download Center.

https://www.intel.com/content/www/us/en/download/19344/intel-graphics-windows-dch-drivers.html

Regards, 

Josue O.  

Intel Customer Support Technician

[a85551]

Hi Josue O

It is clean installation. The windows 10 in guest is newly installed, and installed igfx_win_101.1340.exe(the latest for now) before connect to internet.

I also tried let the windows update to install the graphics driver.

All are same result: all are fine but no brightness control bar, cant adjust the brightness.

[JosueO_Intel]

Hello a85551,

Thank you for the information provided.  

I will proceed to check the issue internally and post back soon with more details. 

Regards, 

Josue O.  

Intel Customer Support Technician

[JosueO_Intel]

Hello a85551,

In this case, since the issue is only present on the Virtual Machine, our recommendation is to contact the VM vendor to get specialized support on their software as this could be directly related to it. 

Hope this information is useful, if you need any additional information, please submit a new question as this thread will no longer be monitored. 

Regards, 

Josue O.  

Intel Customer Support Technician