since Intel Graphics Driver Version 26.20.100.7755 the maximum screen brightness of my Laptop is reduced

[DErlm]

Hardware: Lenovo Thinkpad X1 Carbon 7th Generation with 4K HDR Screen Option

If i check with my dslr i can see pwm flickering even at highest screen brightness with all Graphics Driver Versions after 26.20.100.7584 (last known good version). Expected is that highest setting doesn't show pwm because panel should be steadily lit. Display is much lower than it used to be, to an extent that i can no longer use the laptop outside, which was the main reason why i chose the 500 nit screen option.

Also tested Version that Lenovo provides (.7811) issue still persists.

Adaptive Brightness, and Powersaving disabled in all tests.

Complete List of tested Versions:

26.20.100.6709

.6861

.7212

.7463

.7584

--- all below have the issue

.7755

.7811

27.20.100.8190

.8236

/Update:

CPU: Intel Core i7 8565U

UHD Graphics 620

[AndrewG_Intel]

Hello DErlm

Thank you for posting on the Intel® communities.

In order to check this behavior could you please provide the following information?

1- For testing purposes, by any chance do you have brightness issues when using an external display? Please provide details.

2- When you mentioned (a)"dslr" and (b)"pwm", do you mean the following?

a- digital single-lens reflex camera

b- Pulse-width modulation

3- Could you please provide some screenshots or a short video to illustrate better the behavior? Also, please provide details/steps on how you reproduce the issue.

4- Please provide a Report for Intel® Graphics Drivers following the steps on the below link:

https://www.intel.com/content/www/us/en/support/articles/000005848/graphics-drivers.html

5- DxDiag* report following these steps:

• In the keyboard, press WinLogo key + R.
• In the Run box please type dxdiag and hit Enter.
• Click on Save All Information.
• Open the report.
• Use the option "save all information" to save the .TXT file.
• Attach the report .TXT file to this thread. 

Note:

To attach a file, you must click the “Attach” option on the bottom left-hand corner of the response box. You can attach only 1 file by post.

Best regards,

Andrew G.

Intel Customer Support Technician

[DErlm]

Hi Andrew,

thanks for replying to my request, i try to provide as much information as possible to your questions:

1: I tested with an external monitor, this doesn't change the behavior with the internal monitor, problem still reproducible.

2: yes to both descripions

a: i tested with my digital camera to check for pwm flickering

b: the display backlight in my perticular Laptop uses pulse width modulation to dim the screen brightness

3: i uploaded a video here: https://www.youtube.com/watch?v=Mx4Idjgllyk

in this video i start with Intel Graphics driver version 26.20.100.7584, switch to revision 26.20.100.7755 and back again, you can see the pwm flickering as soon as the newer driver is activated and the display is much darker, i also check if screen brightness is at the highest setting. i set my camera to a shutterspeed of 1/500s to get the effect to show. as soon as the older driver is activated, the highest brightness setting doesn't flicker anymore and is noticeably brighter to the eye.

4&5: i created the reports for each version of the driver and zipped them

Best regards

David

[Eray1]

Make sure to disable Display Power Saving options from here.

[AndrewG_Intel]

Hello DErlm

Thank you for your response and all the details provided.

From the details you provided, we understand that you do not have issues with brightness on an external display but the issue persists only on the built-in display.

Brightness and related features vary from one system to another and usually it requires a customized driver for proper functionality.

Original Equipment Manufacturers (OEMs, e.g. Lenovo™) can modify parameters and add their own requirements to the driver and they perform test and validation on their hardware.

The drivers provided by your OEM for your Intel component might have been changed or customized. This means the graphics drivers from downloadcenter.intel.com are generic and they are meant to be used for reference and testing. We recommend using the OEM driver from Lenovo™, so you don’t lose features or customizations.

Having said that and after checking all the information, this seems to be related to an issue with refresh rate and the use of graphics generic drivers.

We understand you tested Lenovo's latest driver 26.20.100.7811*.

In this case, we kindly recommend addressing this inquiry to your OEM and checking with them for additional customized and updated drivers available for your system, and for available BIOS/firmware updates, fixes, and settings.

Best regards,

Andrew G.

Intel Customer Support Technician

*Links to third-party sites and references to third-party trademarks are provided for convenience and illustrative purposes only. Unless explicitly stated, Intel® is not responsible for the contents of such links, and no third party endorsement of Intel® or any of its products is implied.

[DErlm]

thanks for the response, there is a discussion in the Lenovo Forums about this issue, hope Lenovo responds at some point: https://forums.lenovo.com/t5/ThinkPad-X-Series-Laptops/Latest-Intel-Graphics-Driver-Makes-Display-Dim/m-p/5001872?page=2

Meanwhile 26.20.100.75840 seems to work fine i just have to constantly fight with Windows Update

[AndrewG_Intel]

Hello DErlm

Thank you for your response and for sharing the Lenovo™ Forum link, maybe other users can check it as a reference.

You may also check with Microsoft® Support if there are options or settings you may use to stop Windows® from constantly pushing a driver update.

Best regards,

Andrew G.

Intel Customer Support Technician