Cannot find a backlight controller radeon_acpi asus k555dg

by hamideh   Last Updated August 05, 2018 10:02 AM

I am new to linux. I have an asus k555dg laptop (amd radeon graphic cards). I was trying to install Ubuntu 12.04 lts along with windows 10 X64 and after installation I had the following messages on the screen:

Stopping anac(h)ronistic cron

Stopping system v runlevel compatibility

Stopping cold plug devices

Stopping log initial devices creation

Stopping configure virtual network devices

Stopping enable remaining boot-time encrypted block devices

Speech-dispatcher disabled; edit /etc/default/speech-dispatcher

*asking all remaining process to terminate ….

Please remove your installation media and close tray then press enter.

Each time I boot Ubuntu, I get an error message “[drm:radeon_acpi_init] error Cannot find a backlight controller” .

And the following message every time I shut down:

Could not write bytes: broken pipe

Speech-dispatcher disabled; edit /etc/default/speech-dispatcher

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