I have a ThinkPad X61 running Fedora 8 with kernel 2.6.23.9. This includes thinkpad_acpi module version 0.16 and a video module with no version number other than that of the kernel. With both the thinkpad_acpi and video kernel modules loaded, I see three representations of the display backlight under /sys/class/backlight: acpi_video0 acpi_video1 thinkpad_screen Attempting to set brightness levels using each of these gives the following results: acpi_video0/max_brightness is "100". Echoing values from 0-100 into acpi_video0/brightness has no observable effect on either the integrated LCD display or on an externally-connected VGA monitor. The value in acpi_video0/actual_brightness does change, though at coarser steps. acpi_video1/max_brightness is "100". Echoing values from 0-100 into acpi_video1/brightness changes the brightness of the integrated LCD display. The display goes through sixteen discrete brightness levels. This seems correct, as the same laptop offers sixteen brightness levels when running Windows Vista. However, it is slightly odd that values from 0-19 inclusive have no effect on the display brightness. Values 20-24 set the backlight to its darkest available setting of 20; values 0-19 do nothing at all. thinkpad_screen/max_brightness is "7". This seems incorrect, as the same laptop offers sixteen brightness levels when running Windows Vista. Echoing values 0-7 into thinkpad_screen/brightness changes the brightness of the integrated LCD display. However, even at brightness level 0 the display is still brighter than it can be. It appears that this interface only steps the backlight through the brightest 8 of its 16 possible values. Also, after echoing 0 into thinkpad_screen/brightness, acpi_video1/actual_brightness reports brightness level 60 instead of the minimum level of 20 we can get by using acpi_video1/brightness to set the level. I'll also note that <http://people.freedesktop.org/~hughsient/quirk/quirk-backlight-index.html> states that "The video kernel acpi driver is buggy on quite a few IBM and Lenovo laptops" and recommends unloading or blacklisting it entirely to fix the problem of multiple laptop panel devices showing up in HAL. To summarize, I'm seeing the following glitches here: - three devices in /sys/class/backlight for one piece of hardware - acpi_video0 appears to do nothing useful at all - acpi_video1 works well, except that levels 0-19 are no-ops - thinkpad_screen only exposes the brightest 8 of 16 levels HAL is the main consumer of this information in my working environment, and HAL has good facilities for working around quirky hardware. I'd appreciate feedback on which of the above glitches should be considered true thinkpad_acpi or video module bugs and which I should work around in user-space by defining various HAL quirks. The lack of an X61 row in the compatibility table at <http://ibm-acpi.sourceforge.net/> suggests I'm in uncharted territory. I'm happy to help fill that table in of there are specific tests you'd like me to run. Or is this a more informal process of doing whatever it is I think I should do to test each feature column? Let me know; I'd like to help. Regards, Ben Liblit ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ ibm-acpi-devel mailing list ibm-acpi-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/ibm-acpi-devel
