Comment 0 for bug 1861925

Hi,

I have a acer aspire a315-41 laptop. I have a problem with the Backlight. I can not control.

According to: https://wiki.ubuntu.com/Kernel/Debugging/Backlight

It is : Backlight control does not work, but there are entries in /sys/class/backlight.

The problem is as far I could find:

sanya@Aspire-A315-41:/sys/class/backlight/amdgpu_bl0$ cat brightness
135
sanya@Aspire-A315-41:/sys/class/backlight/amdgpu_bl0$ cat actual_brightness
43500
sanya@Aspire-A315-41:/sys/class/backlight/amdgpu_bl0$ cat max_brightness
255

The brightness read from the HW is not in the range, and when I change the brightness by the keys the value in the brightness file changes too, but the actual_brightness is fix...

I have tried all the steps mentioned in https://wiki.ubuntu.com/Kernel/Debugging/Backlight

Actually I have tried all these kernel startup parameter variants without luck:

GRUB_CMDLINE_LINUX_DEFAULT=""
#GRUB_CMDLINE_LINUX_DEFAULT="video.use_native_backlight=1"
#GRUB_CMDLINE_LINUX_DEFAULT="acpi_osi="
#GRUB_CMDLINE_LINUX_DEFAULT="video.use_bios_initial_backlight=0"
#GRUB_CMDLINE_LINUX_DEFAULT="amdgpu.dcfeaturemask=0x4 amdgpu.abmlevel=2"
#GRUB_CMDLINE_LINUX_DEFAULT="acpi_backlight=video amdgpu.abmlevel=1"
#GRUB_CMDLINE_LINUX_DEFAULT="i8042.nopnp acpi_osi=Linux acpi_backlight=vendor"
#GRUB_CMDLINE_LINUX_DEFAULT="i8042.nopnp acpi_osi=! acpi_osi=\"Windows 2009\" acpi_backlight=vendor"
#GRUB_CMDLINE_LINUX_DEFAULT="i8042.nopnp acpi_osi=! acpi_osi=\"Windows 2009\" acpi_backlight=video"
#GRUB_CMDLINE_LINUX_DEFAULT="acpi_osi=! acpi_osi=\"Windows 2009\" acpi_backlight=vendor"
#GRUB_CMDLINE_LINUX_DEFAULT="i8042.nopnp acpi_osi=! acpi_osi=\"Windows 2009\" acpi_backlight=vendor"
#GRUB_CMDLINE_LINUX_DEFAULT="i8042.nopnp acpi_osi=! acpi_osi=\"Windows 2009\" acpi_backlight=vendor"