kernel-packages team mailing list archive

[Thomas Vachon <vachon@xxxxxxxxxxxx>]

Using the Intel 7260 AC Wireless chipset, there is a noticeable slowdown
and multiple disconnection problem.  When connected to a hotspot it is
unusable (multiple disconnections, ICMP times nearly 8000MS).  Turning
off power management via "iwconfig wlan0 power off" seems to resolve the
issue.

When the power management is on, you see excessive retries and also
spectrum hopping (2.4 to 5.0 and back).  The reported link quality is
reported by iwconfig between 15-25 out of 70 even though the source is
within inches or up to 3 feet away.

When connected to a 802.1b/g/n/a/ac infrastructure network, you will
seep speeds around 2Mbit, and quick dropping to 100-300Kbit on download
(testing via large file gets and HTML5 speed testing).

Turning power management off and blacklisting via echo
'HOOK_BLACKLIST="wireless"' > /etc/pm.d/config.d/blacklist seems to
resoove the issue.  The exessive retries do not exist nor does the
spectrum hopping.  The provisioned speeds in both highly interfere WiFi
areas and interfere-less areas match the expected speeds 50-80Mbit
Download / 8-15Mbit Upload.  Testing via a local large file, similarly
does not have the same issue.

It does appear to be the chipset specifically, because USB tethering or
being wired via ethernet do not exhibit this problem, it is only using
the WiFi chip.

-- 
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https://bugs.launchpad.net/bugs/1319791

Title:
  [Dell Latitude E7440] WiFi issue

Status in “linux” package in Ubuntu:
  Incomplete

Bug description:

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: linux-image-3.13.0-24-generic 3.13.0-24.47
  ProcVersionSignature: Ubuntu 3.13.0-24.47-generic 3.13.9
  Uname: Linux 3.13.0-24-generic x86_64
  ApportVersion: 2.14.1-0ubuntu3
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC1:  vachon    31131 F.... pulseaudio
   /dev/snd/controlC0:  vachon    31131 F.... pulseaudio
  CurrentDesktop: GNOME
  Date: Thu May 15 07:39:15 2014
  HibernationDevice: RESUME=UUID=63c1784a-b66a-498f-ac43-5fea2ee96bdc
  InstallationDate: Installed on 2014-04-03 (41 days ago)
  InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Beta amd64 (20140326)
  MachineType: Dell Inc. Latitude E7440
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-24-generic root=UUID=54753b1d-b028-408f-a48d-71e020359a84 ro quiet splash vt.handoff=7
  RelatedPackageVersions:
   linux-restricted-modules-3.13.0-24-generic N/A
   linux-backports-modules-3.13.0-24-generic  N/A
   linux-firmware                             1.127
  SourcePackage: linux
  UpgradeStatus: No upgrade log present (probably fresh install)
  WifiSyslog: May 15 07:36:03 vachon-dbp kernel: [203016.704005] wireshark[2344]: segfault at 7fffe7106ff8 ip 00007fc51ad8bad5 sp 00007fffe7106ff0 error 6 in libc-2.19.so[7fc51ad0b000+1bc000]
  dmi.bios.date: 02/18/2014
  dmi.bios.vendor: Dell Inc.
  dmi.bios.version: A08
  dmi.board.name: 091TRH
  dmi.board.vendor: Dell Inc.
  dmi.board.version: A00
  dmi.chassis.type: 9
  dmi.chassis.vendor: Dell Inc.
  dmi.modalias: dmi:bvnDellInc.:bvrA08:bd02/18/2014:svnDellInc.:pnLatitudeE7440:pvr01:rvnDellInc.:rn091TRH:rvrA00:cvnDellInc.:ct9:cvr:
  dmi.product.name: Latitude E7440
  dmi.product.version: 01
  dmi.sys.vendor: Dell Inc.

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