[Bug 1506107] Re: Bad webcam video rendering when using XV acceleration on Skylake gpus.

[Mathew Hodson]

** No longer affects: xserver-xorg-video-intel-lts-vivid (Ubuntu)

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Title:
  Bad webcam video rendering when using XV acceleration on Skylake gpus.

Status in HWE Next:
  Fix Released
Status in xserver-xorg-video-intel package in Ubuntu:
  Fix Released
Status in xserver-xorg-video-intel source package in Trusty:
  Invalid
Status in xserver-xorg-video-intel-lts-vivid source package in Trusty:
  In Progress
Status in xserver-xorg-video-intel source package in Vivid:
  In Progress
Status in xserver-xorg-video-intel-lts-vivid source package in Vivid:
  Invalid

Bug description:
  CPU: Intel(R) Core(TM) i3-6100U CPU @ 2.30GHz
  GPU: Intel Corporation Device [8086:1916] (rev 07)
  Webcam: 0bda:57e3 Realtek Semiconductor Corp.

  [Impact] 
  We noticed that webcam output on a wide range of skylake systems contained corruption during certification testing of OEM machines which uses a certain gstreamer pipeline. An example of the corruption is attached.

  [Test Case]
  1. Boot ubuntu 14.04.3 or 15.04 on a machine with a skylake intel GPU and a webcam
  2. Login system and open a terminal.
  4. Execute '$ gst-launch-0.10 v4l2src ! xvimagesink'

  Expect result:
  There should be no visual artifacts during video playing.  The artifacts will look like the attached video and be very obvious in the unfixed package.

  [Regression Potential] 
  Low, the fix is very minimal was included immediately after the 2.99.917 release was made. It consists of 2 parts, a small patch (http://cgit.freedesktop.org/xorg/driver/xf86-video-intel/commit/?id=cc9d7f6777703037d0d7eff346dd350f4d8b3f31) and a configure option change. The configure option change was in lieu of http://cgit.freedesktop.org/xorg/driver/xf86-video-intel/commit/?id=986cb2335c30792e24a7e2b930ecaa3fa051809a which flipped it on unconditionally and only affects i915_bpo in both of these releases as it requires a 4.0 or newer kernel (i915_bpo is a backport of i915 from 4.2 that is only used on skylake). Both of these changes are already in wily's xserver-xorg-video-intel.

  It has been tested on a large number of machines during certification,
  and also by me on sandybridge, ivybridge, broadwell and skylake
  machines.

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