APPLIED [OEM-5.10] Re: [PATCH 00/15][SRU][U/OEM-5.10] Add DRM support for LTTPR non-transparent link training mode

[Timo Aaltonen]

On 24.11.2020 11.12, You-Sheng Yang wrote:
> BugLink: https://bugs.launchpad.net/bugs/1903969
> 
> [Impact]
> 
> On platforms supported DP tunneling over USB 3.2 or so, a Retimer is
> required on the host side to cover insertion loss. On such platforms the
> rtimer firmware maybe configured to use LTTPR (Link Training Tunable PHY
> Repeater) non-transparent mode only, which is only supported in drm-tip
> currently. Without LTTPR support, link training may fail with following
> error messages depending on the data path configuration:
> 
>    i915 0000:00:02.0: [drm] *ERROR* Link Training Unsuccessful
>    i915 0000:00:02.0: [drm] *ERROR* CPU pipe A FIFO underrun
> 
> [Fix]
> 
> Patchset https://www.spinics.net/lists/intel-gfx/msg248700.html
> ("drm/i915: Add support for LTTPR non-transparent link training mode")
> is required to fix this issue. It has been landed to drm-tip and will
> only included to mainline in v5.11.
> 
> Patchset https://patchwork.freedesktop.org/series/76993/ ("Plumb crtc
> state to link training code") is included for link training functions
> prototype changes.
> 
> [Test Case]
> 
> On Dell OptiPlex and WD19 docking station, use following steps to verify:
> 1. disconnect WD19 from OptiPlex, disconnect OptiPlex's power
> 2. attach OptiPlex's power cord
> 3. attach WD19's power cord
> 4. attach DP to WD19
> 5. attach WD19 to OptiPlex
> 6. boot up and check if boot to GUI directly
> 7. `dmesg` and check if aforementioned DRM link training error appears
> 
> [Regression Potential]
> 
> The second patchset pulled for dependency doesn't have too much
> effective changes but refactoring some translation functions, so very
> unlikely to have regressions.
> 
> For the major part, LTTPR support, when LTTPR is either not detected or
> not supported, it will fall back to use transparent mode as it was.
> Otherwise, DP Standard recommends to use LTTPR non-transparent mode for
> link training, so this should be the right way to have best hardware
> support.
> 
> Imre Deak (6):
>    drm/i915: Fix DP link training pattern mask
>    drm/i915: Simplify the link training functions
>    drm/i915: Factor out a helper to disable the DPCD training pattern
>    drm/dp: Add LTTPR helpers
>    drm/i915: Switch to LTTPR transparent mode link training
>    drm/i915: Switch to LTTPR non-transparent mode link training
> 
> Ville Syrjälä (9):
>    drm/i915: s/old_crtc_state/crtc_state/
>    drm/i915: Make intel_dp_process_phy_request() static
>    drm/i915: Shove the PHY test into the hotplug work
>    drm/i915: Split ICL combo PHY buf trans per output type
>    drm/i915: Split ICL MG PHY buf trans per output type
>    drm/i915: Split EHL combo PHY buf trans per output type
>    drm/i915: Split TGL combo PHY buf trans per output type
>    drm/i915: Split TGL DKL PHY buf trans per output type
>    drm/i915: Plumb crtc_state to link training
> 
>   drivers/gpu/drm/drm_dp_helper.c               | 232 +++++++-
>   drivers/gpu/drm/i915/display/intel_ddi.c      | 560 ++++++++++--------
>   drivers/gpu/drm/i915/display/intel_ddi.h      |   6 +-
>   .../drm/i915/display/intel_display_types.h    |  19 +-
>   drivers/gpu/drm/i915/display/intel_dp.c       | 318 +++++++---
>   drivers/gpu/drm/i915/display/intel_dp.h       |  11 +-
>   .../drm/i915/display/intel_dp_link_training.c | 554 ++++++++++++++---
>   .../drm/i915/display/intel_dp_link_training.h |  17 +-
>   drivers/gpu/drm/i915/display/intel_dpio_phy.c |  23 +-
>   drivers/gpu/drm/i915/display/intel_dpio_phy.h |   2 +
>   drivers/gpu/drm/i915/display/intel_hdmi.c     |   7 +-
>   include/drm/drm_dp_helper.h                   |  62 ++
>   12 files changed, 1355 insertions(+), 456 deletions(-)
> 

While it's a big pile, they are queued for 5.11 and oem-5.10 is not a 
stable kernel yet..

applied to oem-5.10, thanks


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