`radeontool light off` does not turn off backlight

Dear Radeon folks,

using radeontool 1.6.2-1.1 from Debian Wheezy/testing [1]

$ sudo radeontool --debug light off Found card 1002:9555 (30000) Radeon found. Base control address is 7f0746826000; base framebuffer address is 7f0735e73000. reading RADEON_LVDS_GEN_CNTL (2d0) is 00000000 writing RADEON_LVDS_GEN_CNTL (2d0) -> 00000000

does not turn off the backlight of the laptop monitor. This is a Lenovo G555 laptop with a ATI Radeon HD 4200 graphic device [2].

Do I need to submit a report to Freedesktop.org’s Bugzilla bug tracking system?

Thanks,

Paul

[1] http://packages.debian.org/wheezy/radeontool [2] https://en.wikipedia.org/wiki/Lenovo_G555