[SRU][B/OEM-B/C/D/E][PATCH v2 0/4] Audio doesn't work after s3 or s4 on cnl and glk machines

[Hui Wang]

BugLink: https://bugs.launchpad.net/bugs/1826868

The patch is already in the v5.2-rc1, so don't send the patch
to unstable.

In the V2, I added 3 more patches. The 0001-xxx.patch is for fixing
the issue of "audio doesn't work after s3/s4 on cln and glk machines",
but it introduces a new issue of "screen flickering when CDCLK changes",
So I added 0002/3/4-xxx.patch to fix the new issue.

[Impact]
After s3 or s4, the hdmi audio driver will re-probe the hw, if the hdmi
monitor is not plugged before s3 or s4, the re-probe will fail on cnl
and glk machines.

[Fix]
Keep the cdclk alive when re-probing

[Test Case]
I applied the patches to bionic kernel and disco kernel, and tested them
on Whiskeylake, cannonlake, kabylake, skylake and geminilake
machines, before s3, I verified analogue audio, hdmi audio and screen
dispaly all worked well, then let the system enter s3 and resume, recheck
the analogue audio, hdmi audio and screen display, all worked well too.
And repeated the test 5 times.


[Regression Risk]
Low. I have tested the patched kernel on different Dell and Lenovo machines,
they include Whiskeylake, cannonlake, kabylake, skylake and geminilake.



Imre Deak (2):
  drm/i915: Save the old CDCLK atomic state
  drm/i915: Remove redundant store of logical CDCLK state

Ville Syrjälä (2):
  drm/i915: Force 2*96 MHz cdclk on glk/cnl when audio power is enabled
  drm/i915: Skip modeset for cdclk changes if possible

 drivers/gpu/drm/i915/i915_drv.h      |   6 +-
 drivers/gpu/drm/i915/intel_audio.c   |  57 +++++++++
 drivers/gpu/drm/i915/intel_cdclk.c   | 171 ++++++++++++++++++++-------
 drivers/gpu/drm/i915/intel_display.c |  56 +++++++--
 drivers/gpu/drm/i915/intel_drv.h     |  22 +++-
 5 files changed, 257 insertions(+), 55 deletions(-)

-- 
2.17.1