Re: [PATCH v3 0/4] Enable lspcon support for GEN9 devices

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Jul 05, 2016 at 06:35:46PM +0530, Shashank Sharma wrote:
> 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@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@60 modeset with:
> - BXT-T board
> - Single HDMI 4k@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@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 in 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

This thing seems to be missing a lot of stuff:
- where is the EDID etc. handling?
- based on my DDI output_types stuff, I was expecting to see an
  lspcon .compute_output_type() hook that returns whether we need
  LS or PCON mode. Can't see anything of the sort here.

Also the main patch [1] of my DDI output_types series still didn't
get reviewed...

[1] https://patchwork.freedesktop.org/patch/94581/

> 
>  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       | 145 ++++++++++++++++++++++++++++++
>  include/drm/drm_dp_dual_mode_helper.h     |  26 ++++++
>  8 files changed, 369 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/gpu/drm/i915/intel_lspcon.c
> 
> -- 
> 1.9.1

-- 
Ville Syrjälä
Intel OTC
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