On Thu, 22 Nov 2007, Arkadiusz Miskiewicz wrote: > On Saturday 17 of November 2007, Arkadiusz Miskiewicz wrote: > > On Saturday 17 of November 2007, you wrote: > > > On Sat, 17 Nov 2007, Arkadiusz Miskiewicz wrote: > > > > > I'm using currect linux from 2.6.24 git tree (pulled today). Few days > > > > > ago brightness setting stopped working. Do you have any idea which > > > > > patch could break things before I start bisecting? > > > > > > > > FYI: Tested v0.18-20071112 from sourceforge, too - the same problem, > > > > brightness controll doesn't work. > > > > > > How do you control the brightnes? Using the keyboard? Using > > > /proc/acpi/ibm/brightness? Using something else? > > > > I've pasted log from my /proc tests in first email where I tried to control > > brightness via ibm/brightness and ibm/cmos proc files. Both do not work. > > > > Also fn+home, fn+end from keyboard doesn't cause any LCD brightness change > > (only level value in /proc/acpi/ibm/brightness changes). > > I found guilty part. It was radeon opensource X.Org driver. It started messing > with bios_4_scratch and bios_5_scratch (and 6_scratch) registers. > > For example it zeroes all bits in bios_4_scratch (0x0020). I found out that > not touching 3 bit (counting from 0) in bios_4_scratch makes brightness > setting possible again. > > Do you know meaning of this bit? No, but it looks like a "don't mess with it, it is for BIOS use" case to me. > ati driver also messes with 0-3 bits (zeroes these; it actually writes 0xff00 > into 5_scratch register) in bios_5_scratch (0x0024) which AFAIK keep > brightness level, right? > > Are you aware of any other bits that have influence on backlight that should > be not touched? IMO, it appears none of the bios_*_scratch registers should ever be touched, *unless* one knows what they do (perhaps the X.org people *do* know, but *I* don't, and I don't know if they know :-) ). If they do know what they are doing (which is actually likely), and they do intend to disable backlight control by the BIOS, it means that you need extra setup on a lot of thinkpads when X.org loads. Worse, it is thinkpad-model dependant. Do you know the email address of the X.org developers responsible for these drivers? It seems it would be wise to talk to them, and get to know what they need done, so that I can add the model-dependent knowledge inside thinkpad-acpi. Doing it in userspace (HAL) is going to be trouble. -- "One disk to rule them all, One disk to find them. One disk to bring them all and in the darkness grind them. In the Land of Redmond where the shadows lie." -- The Silicon Valley Tarot Henrique Holschuh ------------------------------------------------------------------------- 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
