Could someone please let me know how to apply this patchwork to mainstream kernel source?

I tried on the latest 4.6-rc5 and it failed. It did work on drm-intel-nightly though which is a not mainstream branch.

On 26 April 2016 at 07:45, <bugzilla-daemon@freedesktop.org> wrote:

Comment # 52 on bug 89055 from dwk128@gmail.com
I can confirm that this works for me on SKL, i5-6200U dell xps 13 9350. There
used to be a crash at every boot and two on suspend, with external HDMI plugged
in. I patched the drm-nightly kernel and compiled it manually.
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~ Prasad Bhat