[0/4] Implement Wa_14021768792 to bypass m_n ratio limit

Message

Nautiyal, Ankit K March 21, 2025, 11:26 a.m. UTC

For Platforms that support higher link rates, there is a limitation on
Link M /Link N ratio.
If the CEILING( Link M / Link N ) ratio is greater than 10.0, then
hardware cannot support the given resolution / refresh rate at the given
configuration.
For BMG Wa_14021768792 helps to bypass this limitation and allows it to
support the ratio till 15.0.

This series adds the missing restrictions for earlier platforms and adds
the Wa_14021768792 for BMG as per Bspec:49266

Rev2:
-Drop new member link_n_extended.
-Avoid WA framework for XE

Rev3:
-Refactor to just add the extended link_n just before writing and scrub
it just after read.

Rev4:
-Rebase

Ankit Nautiyal (4):
  Add bits for link_n_exended for DISPLAY >= 14
  drm/i915/display: Limit m/n ratio to 10 for display > 12
  drm/i915/display: Add bits for Wa_14021768792 for linkm/n ratio > 10
  drm/i915/display: Implement Wa_14021768792 for BMG DP for link_m/n
    ratio > 10

 drivers/gpu/drm/i915/display/intel_display.c  | 160 +++++++++++++++++-
 drivers/gpu/drm/i915/display/intel_display.h  |  12 +-
 .../drm/i915/display/intel_display_types.h    |   2 +
 drivers/gpu/drm/i915/display/intel_dp.c       |  66 ++++++--
 drivers/gpu/drm/i915/display/intel_dp.h       |   4 +
 drivers/gpu/drm/i915/display/intel_dp_mst.c   |  35 ++--
 drivers/gpu/drm/i915/display/intel_fdi.c      |  14 +-
 drivers/gpu/drm/i915/i915_reg.h               |   7 +
 8 files changed, 255 insertions(+), 45 deletions(-)