Did this issue start happening after an update/upgrade? ... No, i just got this laptop (second hand) and promptly installed Lubuntu. It was made in 2013. It uses a hybrid graphics system. ... Since dimming works at the BIOS screen, this seems to be a software issue.
Was there a prior kernel version where you were not having this particular problem? ... Haven't tested prior versions. Willing to do so. Tested with 4.11 RC8 and the problem is still present. When installing with dpgk, the following warnings were returned: update-initramfs: Generating /boot/initrd.img-4.11.0-041100rc8-generic W: Possible missing firmware /lib/firmware/i915/kbl_huc_ver02_00_1810.bin for module i915 W: Possible missing firmware /lib/firmware/i915/bxt_huc_ver01_07_1398.bin for module i915 W: Possible missing firmware /lib/firmware/i915/skl_huc_ver01_07_1398.bin for module i915 Thanks for your help. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1685620 Title: Screen flashes continuously when brightness set to lower than 100% using fn keys on Samsung NT200B5C-STW/R laptop running Lubuntu 17.04 x64 Status in linux package in Ubuntu: Incomplete Bug description: Followed instructions here: https://wiki.ubuntu.com/Kernel/Debugging/Backlight Category: Backlight control does not work, but there are entries in /sys/class/backlight System: Samsung NT200B5C-STW/R notebook, Lubuntu 17.04 x64 More info: - Dimming the screen in the BIOS using the function keys works as expected, so doesn't appear to be a hardware issue. - After installing Lubuntu 17.04 x64, the screen is at full brightness. - Attempting to dim the screen using the function keys does not work. However the brightness applet is displayed and /sys/class/backlight/intel_backlight/brightness file is modified. However, at lower settings, instead of dimming, the backlight appears to switch on and off continuously. If the brightness is set back up to 100%, the flashing ceases. The on off cycling appears to increase in frequency the lower the brightness setting. - Ran all debugging info commands. Note that dsdt.dat is lowercase. See backlight.zip (attached as one zip as the site isn't allowing multiple attachments for some reason) - Setting acpi_backlight=vendor ... No change - /sys/class/backlight/intel_backlight/brightness is present. ... Changing the number has the same effect as using the Fn keys. Values lower than 100% cause the screen to cycle on and off continuously. - Kernel param: video.use_bios_initial_backlight=0 ... same behavior. - Kernal param: acpi_osi= ... same behavior - Kernel version is: 4.10.0-19-generic - Kernel param: acpi.brightness_switch_enabled=0 ... same behavior - $ dmesg | grep 'ACPI: Video' [ 2.481461] ACPI: Video Device [PEGP] (multi-head: yes rom: yes post: no) [ 2.482043] ACPI: Video Device [GFX0] (multi-head: yes rom: no post: no) - $ lspci |grep VGA 00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09) ProblemType: Bug DistroRelease: Ubuntu 17.04 Package: linux-image-4.10.0-19-generic 4.10.0-19.21 [modified: boot/vmlinuz-4.10.0-19-generic] ProcVersionSignature: Ubuntu 4.10.0-19.21-generic 4.10.8 Uname: Linux 4.10.0-19-generic x86_64 AlsaVersion: Advanced Linux Sound Architecture Driver Version k4.10.0-19-generic. ApportVersion: 2.20.4-0ubuntu4 Architecture: amd64 ArecordDevices: **** List of CAPTURE Hardware Devices **** card 0: PCH [HDA Intel PCH], device 0: ALC269VC Analog [ALC269VC Analog] Subdevices: 1/1 Subdevice #0: subdevice #0 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: flgc 1174 F.... pulseaudio Card0.Amixer.info: Card hw:0 'PCH'/'HDA Intel PCH at 0xf7e30000 irq 34' Mixer name : 'Realtek ALC269VC' Components : 'HDA:10ec0269,144dc0e4,00100202 HDA:80862806,80860101,00100000' Controls : 28 Simple ctrls : 11 CurrentDesktop: LXDE Date: Sun Apr 23 20:10:20 2017 HibernationDevice: RESUME=UUID=145d228c-4542-4aab-901e-894d929d2085 InstallationDate: Installed on 2017-04-23 (0 days ago) InstallationMedia: Lubuntu 17.04 "Zesty Zapus" - Release amd64 (20170412) MachineType: SAMSUNG ELECTRONICS CO., LTD. 400B4C/400B5C/200B4C/200B5C ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.10.0-19-generic.efi.signed root=UUID=3312063b-5d45-48b3-9e73-34065c10b162 ro quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-4.10.0-19-generic N/A linux-backports-modules-4.10.0-19-generic N/A linux-firmware 1.164 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 08/14/2013 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: P05AAZ.033.130814.dg dmi.board.asset.tag: No Asset Tag dmi.board.name: SAMSUNG_NP1234567890 dmi.board.vendor: SAMSUNG ELECTRONICS CO., LTD. dmi.board.version: SEC_SW_REVISION_1234567890ABCD dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 9 dmi.chassis.vendor: SAMSUNG ELECTRONICS CO., LTD. dmi.chassis.version: N/A dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP05AAZ.033.130814.dg:bd08/14/2013:svnSAMSUNGELECTRONICSCO.,LTD.:pn400B4C/400B5C/200B4C/200B5C:pvrP05AAZ:rvnSAMSUNGELECTRONICSCO.,LTD.:rnSAMSUNG_NP1234567890:rvrSEC_SW_REVISION_1234567890ABCD:cvnSAMSUNGELECTRONICSCO.,LTD.:ct9:cvrN/A: dmi.product.name: 400B4C/400B5C/200B4C/200B5C dmi.product.version: P05AAZ dmi.sys.vendor: SAMSUNG ELECTRONICS CO., LTD. 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