Can't adjust backlight on Lenovo y500 with nvidia drivers

asked 2015-06-12 01:14:13 -0500

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I've been unable to adjust my laptop's backlight ever since I upgraded to Fedora 22. I've been using the akmod-nvidia package because nouveau seems to be unable to output video to an external monitor on my particular laptop.

I tried adding acpi_osi=Linux and acpi_backlight=vendor and changing to various other combinations, but to no avail.

Finally, I remembered what I had done in Fedora 21: use the nvidiabl kernel module. Unfortunately, the nvidiabl module won't compile under linux 4.0+, but luckily someone wrote this patch:

In the file nvidiabl-module.c, I changed these lines:

    for (iii = 0 ; iii < sizeof(backlight_type_ids) ; iii++) {
            if (strnicmp(bl_type, backlight_type_ids[iii].id, sizeof(bl_type)) == 0) {

to these:

    for (iii = 0 ; iii < sizeof(backlight_type_ids) ; iii++) {
            if (strncasecmp(bl_type, backlight_type_ids[iii].id, sizeof(bl_type)) == 0) {
            if (strnicmp(bl_type, backlight_type_ids[iii].id, sizeof(bl_type)) == 0) {

With the above changes, the module compiles successfully on linux 4.0.4-303 If you want complete instructions on using dkms to compile this module, follow the first part of the instructions on this page:

UPDATE: While this patch "works," it is extremely buggy. Often, when I launch an application on my y500, the screen brightess resets itself to 100%, but the brightness slider doesn't move. There is some additional work needed to make this module 4.0+ ready. Why doesn't nvidia add this functionality to their proprietary drivers???

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why no install brightness? Brightness Controller is the only GUI application for Linux that allows you to control brightness of your primary and secondary display from the same place. It is a software based dimmer.

dnf -y install
davidva gravatar imagedavidva ( 2015-06-28 19:32:54 -0500 )edit

Having a program that allows the brightness to be adjusted does no good without the driver required to make it work.

kg6zvp gravatar imagekg6zvp ( 2015-10-21 10:35:53 -0500 )edit