roblm wrote:Your laptop has a particularly difficult problem since no entries are found in /sys/class/backlight or /proc/acpi, which indicates no method of
backlight control has been found. I have only seen this in two other messages I have read from other people with similar brightness problems,
out of about 200 messages. I assume you haven't tried installing any proprietary driver for your Radeon card.
As far as I know, the vga_switcheroo command only works to switch GPUs if your system has a so called hardware mux (multiplexer) with a
setting in the BIOS to control it, but even then not all systems can use this, and it only works with the open source drivers. The following
command is supposed to check your system if this command is available: grep -i switcheroo /boot/config-*
grep -i switcheroo /boot/config-*
To see if there is any brightness control try using the xrandr command:
xrandr --output LVDS1 --X (values below 1.0 decrease brightness)
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 1920 x 1080, current 1920 x 1080, maximum 1920 x 1080
default connected 1920x1080+0+0 (0x17e) normal (normal) 0mm x 0mm
You probably should first try upgrading to Mint 15 which has the newer 3.8.0-19 kernel.
You can also try editing the grub file by replacing:
to one of the following lines. You can try this with UEFI BIOS and then again with the Legacy BIOS option.
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash noapic"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi=force noapic nolapic"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=force acpi_backlight=vendor”
GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash acpi_osi=Linux”
GRUB_CMDLINE_LINUX_DEFAULT="quite splash acpi_osi=Linux acpi_backlight=vendor"
Save the file and then open the Terminal and type: sudo update-grub, and reboot but be prepared for a similar problem you had when you
tried this with "acpi_backlight=vendor"
You can try installing a proprietary driver in System Tools > System Settings > Software Sources > Additional Drivers.
I've tried those settings before, and they've left me with a black screen after boot..
I have the strange feeling that something is really really wrong with my mint installation - or it just doesn't work out with my hardware..
vgaswitcheroo was working before and without changing anything, it stopped working (as I said I already had the gpu disabled and it was working fine, except the brightness). Also, I can no longer access protected WiFis (http://forums.linuxmint.com/viewtopic.php?f=49&t=136298) which basically forces me to move away from mint at that point of time. Too much trouble, too much time wasted
And the worst thing is, I did not even change anything (no driver changed, no updates, etc...)
Thank you for your help nevertheless