[Intel-gfx] [PATCHv3 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.

Patch   1/4   :Moves finding unused crtc to a common function
Patch   2,3/4 :Update pll config's crtc_mask/dpll hw_state to
                use in upfront link train
Patch   4/4   :Upfront implementation for DDI platforms
                (for now, tested on BXT B1).

Changes from v2:
* Rebased on top of intel_dpll_mgr.c code.
* Use drm_atomic_commit instead of atomic_helper_dpms, since the
  later uses crtc->acquire_ctx used also in legacy paths.
* Using a drm_atomic_state helps in using the shared_dpll APIs
  as is, thus keeping the upfront code away from changing pll
  internals directly.
* Fixed locking/retry/backoff logic in upfront according to
  atomic implementation.
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 v2:    https://patchwork.freedesktop.org/patch/72207/
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: Make finding unused crtc as a generic function
  drm/i915: Store the dpll config in crtc_state->shared_dpll
  drm/i915: Update dpll_hw_state if mask is same
  drm/i915/dp: Enable Upfront link training for typeC DP support on BXT

 drivers/gpu/drm/i915/intel_ddi.c      |  46 +++++++++
 drivers/gpu/drm/i915/intel_display.c  |  74 ++++++++------
 drivers/gpu/drm/i915/intel_dp.c       | 180 +++++++++++++++++++++++++++++++++-
 drivers/gpu/drm/i915/intel_dpll_mgr.c |   8 +-
 drivers/gpu/drm/i915/intel_drv.h      |   7 ++
 5 files changed, 279 insertions(+), 36 deletions(-)

-- 
1.9.1