Dell Latitude E5520

Hardware
00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09) 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) 00:16.0 Communication controller: Intel Corporation 6 Series/C200 Series Chipset Family MEI Controller #1 (rev 04) 00:1a.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #2 (rev 04) 00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 04) 00:1c.0 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 1 (rev b4) 00:1c.1 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 2 (rev b4) 00:1c.2 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 3 (rev b4) 00:1c.5 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 6 (rev b4) 00:1c.6 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 7 (rev b4) 00:1d.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #1 (rev 04) 00:1f.0 ISA bridge: Intel Corporation HM65 Express Chipset Family LPC Controller (rev 04) 00:1f.2 SATA controller: Intel Corporation 6 Series/C200 Series Chipset Family 6 port SATA AHCI Controller (rev 04) 00:1f.3 SMBus: Intel Corporation 6 Series/C200 Series Chipset Family SMBus Controller (rev 04) 02:00.0 Network controller: Intel Corporation Centrino Advanced-N 6205 [Taylor Peak] (rev 34) 09:00.0 FireWire (IEEE 1394): O2 Micro, Inc. 1394 OHCI Compliant Host Controller (rev 05) 09:00.1 SD Host controller: O2 Micro, Inc. Integrated MMC/SD controller (rev 05) 09:00.2 Mass storage controller: O2 Micro, Inc. O2 Flash Memory Card (rev 05) 0a:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5761 Gigabit Ethernet PCIe (rev 10)

Special keys FN+ does not work
If you are getting unknown key press in kernel log (dmesg) you will need to setup keycodes for the special keys, you can let udev take care of it (if you use udev) by 'keymap' USE flag, manualy using 'setkeycodes' or use a mdev-like-a-boss script https://raw.github.com/slashbeast/mdev-like-a-boss/master/keymaps/dell.sh

No sound after resume from hibernation
Sometimes (usualy) after resume there is no sound or some features does not work like muting speakers when headphones are connected. The fix is to load snd-hda-intel with option probe_mask=1, you can do this by creating a file under /etc/modprobe.d/ with

Processor stuck at 800 MHz regardless of CPU governor
BIOS can force operating system to limit max cpu speed to given value when there is not enough input power, broken or unknow PSU, overheat issue or because bug in the BIOS itself, which in my case is the last one. After a while, when computer is idling, around 50'C on cpu with fan off the cpu were blocked at 800 MHz, you can check it by cpufreq-info | grep 'frequency should be within 800 MHz and' If you see '800 MHz and 800 MHz' then the BIOS has spoken.

Fix: Let know kernel to ignore the forceful request from BIOS to limit cpu speed, append 'processor.ignore_ppc=1' to kernel's boot params.

Backlights does not turn off with LID closed
You will need acpid and a script to catch the lid open/close events turn off the screen.

Example of /etc/acpi/default.sh with abillity to turn off the backlights whenever LID is closed. In this very example when you open the LID brightness will be set to 80%
 * 1) !/bin/sh

set $*

group=${1%%/*} action=${1#*/} device=$2 id=$3 value=$4

log_unhandled { logger "ACPI event unhandled: $*" }

case "$group" in	button)		case "${action}" in			'lid') if grep -q closed /proc/acpi/button/lid/*/state; then echo 0 >/sys/class/backlight/intel_backlight/brightness elif grep -q open /proc/acpi/button/lid/*/state; then echo "$(( ($(cat /sys/class/backlight/intel_backlight/max_brightness)/10)*8 ))" >/sys/class/backlight/intel_backlight/brightness fi esac ;;	battery