Dell Latitude E7270

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Reason: Needs a hardware table and a function keys section (Discuss in Talk:Dell Latitude E7270)

Sound

Audio output via the headphone port does not work if the microphone is muted when the laptop is started. Unmuting the microphone fixes the issue, it can be savely muted afterwards.

Display

According to cat /sys/kernel/debug/dri/0/i915_edp_psr_status: 

Sink_Support: yes
Source_OK: no
Enabled: no
Active: no
Busy frontbuffer bits: 0x000
Re-enable work scheduled: no
Main link in standby mode: no
HW Enabled & Active bit: no

The FullHD panel supports psr, but the i915 psr implementation for skylake has Known Bugs

Frozen CPU Frequency Scaling

If you experience frequency scaling freezing, i.e. your cpu stays at the lowest idle frequency follow these steps:

  1. shutdown your laptop
  2. remove back cover
  3. unplug battery
  4. hold power button for 20s (Count to 40 to be sure)
  5. replug battery
  6. attach back cover
  7. start laptop and retest

See also FS#56866.

Touchpad

Support for the ALPS touchpad included in Dell E7270 & E7470 was only added in Linux kernel 4.9, with some issues accidentally introduced in 4.13 and then refixed in 4.15. The fixes were backported to Linux LTS kernels 4.9 & 4.14. Earlier kernels did not recognize the touchpad and used it in its emulated PS/2 mode, so changing options (like scroll direction, multi-touch gestures, etc.) was not possible.

What does not work

  • Fingerprint Reader (0a5c:5834)
  • DW5811e stops working after suspend, presumably the UEFI does initial configuration, needs more testing
    • Per LKML runtime power management does not work for the chip (EM7455) used in the DW5811e, disabling runtime pm and reseting the device makes it usable.