[Intel-gfx] [PATCHv2 0/4] Add USB typeC based DP support for BXT platform

[Durgadoss R]

This patch series adds upfront link training support to enable
USB type C based DP on BXT platform.

To support USB type C alternate DP mode, the display driver needs to
know the number of lanes required by the DP panel as well as number
of lanes that can be supported by the type-C cable. Sometimes, the
type-C cable may limit the bandwidth even if Panel can support
more lanes.

The goal is to find out the number of lanes which can be supported
using a particular cable so that we can cap 'max_available_lanes'
to that number during modeset.

Patches 1/4 :Refactoring/exporting DDI functions required
             to do upfront link train
Patch   2/4 :Moves finding unused crtc to a common function
Patch   3/4 :Make intel_ddi_get_crtc_encoder handle non-atomic paths
Patch   4/4 :Upfront implementation for DDI platforms
             (for now, tested on BXT A1).

Changes from v1:
* Using atomic_helper_dpms() to do DPMS off for upfront link
  training, instead of using load detect functions.
* Made intel_get_shared_dpll handle non-atomic paths by
  duplicating the required shared_dpll_config and then working
  on top of it. This helps in upfront link train code not
  directly touch the 'pll/pll->config' internals.
* Fixed the link_bw update logic in intel_dp_get_link_retry_params()
  for non-HBR2 panels.
* As per comments on earlier version, merged few patches
  (that added new functions) with the upfront link train patch,
  to facilitate easy review.

Link for v1:    https://patchwork.freedesktop.org/patch/67784/
Link for RFCv2: https://patchwork.freedesktop.org/patch/61776/
Link for RFCv1: https://patchwork.freedesktop.org/patch/59589/

Durgadoss R (4):
  drm/i915/dp: Export enable/disable_shared_dpll methods
  drm/i915: Make finding unused crtc as a generic function
  drm/i915/dp: Use legacy get_crtc_encoder in non-atomic paths
  drm/i915/dp: Enable Upfront link training for typeC DP support on BXT

 drivers/gpu/drm/i915/intel_ddi.c     | 105 ++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_display.c |  79 ++++++++++++++++++-----
 drivers/gpu/drm/i915/intel_dp.c      | 122 ++++++++++++++++++++++++++++++++++-
 drivers/gpu/drm/i915/intel_drv.h     |  13 ++++
 4 files changed, 301 insertions(+), 18 deletions(-)

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1.9.1