Hardware: Clevo P751TM1 ( which is using the same motherboard as p775tm1, but it has a 15 inch screen ), CPU: i5-8400, GPU: GTX 1070 laptop
OS: Ubuntu 20.04.6 with default kernel 5.15.0-100
BIOS & EC: bios 1.07.29, ec 1.07.16. It is already the latest version and will not be updated again :(
when I use 390.xx driver, brightness control is pretty good. but any other updated versions of drivers are unable to control screen brightness. In ubuntu 20.04 Additional Drivers, I tried 390.xx 470.xx 525.xx 535.xx.
I thought the newer kernel might solve the problem, so last month, I tried reinstalling the system to ubuntu 22.04.3, it’s default kernel is 6.x ( I can’t remember exactly what it is ), and I can also try installing the 545.xx driver in the additional driver. installed 545.29.06 driver, which claimed to solve the screen brightness issue, but the issue still not been resolved.
and in ubuntu 22.04, I can’t install 390.xx, it always fails. for my eyes, I back to 20.04.
for each attempt mentioned above, I all tested different kernel parameters:
acpi_backlight=video
acpi_backlight=vendor
acpi_backlight=native
acpi_backlight=none
it all failed.
Interestingly，in 390.xx, I also tested above kernel parameters, but it always succeeds, even with acpi_backlight=none.
390.157-with-no-param-nvidia-bug-report.log.gz (221.6 KB)
535.161-with-no-param-nvidia-bug-report.log.gz (736.4 KB)
acpidata-535.161.zip (201.7 KB)
I think my situation is same as this, but it closed with no workaround, so i have to open a new topic.