[Intel-gfx] [PATCH v4 0/4] Enable lspcon support for GEN9 devices

[Shashank Sharma]

LSPCON is essentially a dp++->hdmi adapter with dual mode of operation.

These modes are:
- Level Shifter mode: In LS mode, this device works as a type2 dp->hdmi
passive dongle, which steps up DP++ output to appropriate HDMI 1.4 signal.
This mode doesn't do any conversion at the protocol level.

- Protocol Converter mode: In PCON mode, this device acts as an
active DP++->HDMI 2.0 dongle, which converts the DP++ output to
compatible HDMI 2.0 output. In PCON mode, lspcon can support 4k at 60
outputs, using DP HBR2 mode.

Many of Intel GEN9 devices come with in-built lspcon card
in motherboartd down mode. This patch series adds support for
lspcon devices in I915 driver.

While unit-testing this code, I was able to see a 4k at 60 modeset with:
- BXT-T board
- Single HDMI 4k at 60 display (ACER S)
- Ubuntu 14.04 desktop

V2: Worked on review comments from Ville
- In general, Ville suggested not to use the dual personality of
  DDI to drive lspcon, so this patch set drives it just as DP++ display.
  There is no separate detection for lspcon (hpd_pulse is good enough), and
  its being driven as a DP display with special initialization and EDID
  read sequence. To be able to do this, we driving lspcon in PCON mode only,
  where it can serve both HDMI1.3/HDMI1.4 sinks as well as 4k at 60 capable
  HDMI 2.0 sinks. So compared to previous series, there is one patch less,
  as we have dropped lspcon detection patch.


V3: Addressed review comments from Rodrigo
    Details available with respective patch.

V4: Addressed review comments from Ville
    Details available with respective patch.

Shashank Sharma (4):
  drm: Helper for lspcon in drm_dp_dual_mode
  drm/i915: Add lspcon support for I915 driver
  drm/i915: Parse VBT data for lspcon
  drm/i915: Enable lspcon initialization

 drivers/gpu/drm/drm_dp_dual_mode_helper.c | 103 ++++++++++++++++++++++++
 drivers/gpu/drm/i915/Makefile             |   1 +
 drivers/gpu/drm/i915/i915_drv.h           |   5 ++
 drivers/gpu/drm/i915/intel_bios.c         |  49 ++++++++++++
 drivers/gpu/drm/i915/intel_ddi.c          |  29 ++++++-
 drivers/gpu/drm/i915/intel_drv.h          |  13 ++-
 drivers/gpu/drm/i915/intel_lspcon.c       | 127 ++++++++++++++++++++++++++++++
 include/drm/drm_dp_dual_mode_helper.h     |  26 ++++++
 8 files changed, 351 insertions(+), 2 deletions(-)
 create mode 100644 drivers/gpu/drm/i915/intel_lspcon.c

-- 
1.9.1