[Bug 99650] Suspend and resume take long time on Dell XPS 13 9360 (Kaby Lake)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=99650

--- Comment #7 from David Weinehall <david.weinehall at intel.com> ---
Something seems to be really wrong with that graph you posted (suspend only
taking 0.011ms)--or did you filter these figures to only contain resume time?

Anyhow, let's start with the low-hanging fruit:

The 206ms spent in skl_update_crtcs() is the VBT-mandated panel on-timeout
(200ms) + DP link training. There's also cdclk programming which takes a few
milliseconds. This covers intel_display_resume(), which is the biggest
"culprit".

The ~16ms schedule_timeout() is where we wait for vblank before programming
vblanks; that section is covered by a FIXME and a TODO, so that bit is a known
issue.

The remaining slow-poke is intel_opregion_setup() (63ms). I must admit that I
cannot explain that slowdown without diving further into the code; our kabylake
here does not exhibit this behaviour; I just ran a test on a machine in our
lab--that function took roughly 6ms.

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