Hello Lyude, Sorry to respond so late. But my work had me exhausted these last days. Add to this that the laptop returned to Lenovo for repair and that's it. The first solution works a bit better than no addition to the kernel line on boot but it is still not perfect and as smooth than on windows 7. But, for now, I can live with that waiting to Ubuntu to ship the latest kernel or back port the modification for my problem. Thanks a lot for your help and answer and please forgive my late answer. Have a nice day! Le 02/03/2015 17:23, Lyude a écrit : > On Sat, 2015-02-28 at 11:17 -0300, Henrique de Moraes Holschuh wrote: >> On Sun, 22 Feb 2015, Georges Giralt wrote: >>> I own a brand new Lenovo E540 (20C600JHFR) fitted with a full HD LCD >>> screen. >>> >>> I've installed Ubuntu 14.04 LTS and exploring the syslog file for >>> unsupported hardware I've found the following message : >>> ======== >>> thinkpad_acpi: Unsupported brightness interface, please contact >>> ibm-acpi-devel@xxxxxxxxxxxxxxxxxxxxx >>> [ 11.725474] thinkpad_acpi: This ThinkPad has standard ACPI backlight >>> brightness control, supported by the ACPI video driver >>> [ 11.725476] thinkpad_acpi: Disabling thinkpad-acpi brightness events >>> by default... >>> ======== >>> >>> I noticed that the brightness control is very coarse instead of the >>> smooth control experienced in Windows >>> How could I help ? >> The brightness control is done by the gpu on just about every laptop >> nowadays, so you should talk to the people behind the gpu drivers and x.org. >> > Hello! I am one of these people :). The problem probably lies in the > fact you're using Ubuntu LTS, specifically the fact it's using an older > Linux kernel. Backlights changed a LOT with Windows 8 laptops. > Originally we used to control it via ACPI, but now like Henrique said it > is done by the GPU. In the past kernel versions this caused a lot of > issues some applications try to use the ACPI backlight control over the > GPU backlight, and many times the ACPI backlight control is at best, > broken, on Windows 8 laptops. It's supposed to be up to the kernel to > hide the ACPI backlight interface on such laptops. We used to try to > maintain a list of devices in order to do this, but this turned out to > be a huge hassle. Eventually the kernel guys came up with a better way > to do this, but I don't exactly remember what that way was (but it does > work thankfully :) > > There's a couple of solutions to fix the backlight control on this, > although it *may* cause your backlight settings to be reset upon reboot. > I do warn you I might be wrong with some of these, it's been a while > since I've dealt with this problem but I'm pretty sure these are the > solutions for it. > > The best solution next to using a newer kernel is adding: > > video.use_native_backlight=1 > > to the kernel command line. If your kernel doesn't support that, can try > > acpi_osi="!Windows 2012" > > The above solution can lead to a couple of other things breaking, or > unbreaking. Generally it's one you want to avoid since having to specify > an acpi OSI is generally considered a bug (ACPI should be the same > across operating systems). > > The original bug discussing this issue can be found here: > https://bugzilla.kernel.org/show_bug.cgi?id=51231 let me know if you > have any questions. > > Cheers, > Lyude -- If the only tool you have is a hammer, you tend to see every problem as a nail. Abraham Maslow A British variant : Any tool can serve as a hammer but a screwdriver makes the best chisel. ------------------------------------------------------------------------------ Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ ibm-acpi-devel mailing list ibm-acpi-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/ibm-acpi-devel
