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67fba3f1c7
The DP PHY vswing/pre-emphasis level programming the driver does is
related to the DPTX -> first LTTPR link segment only. Accordingly it
should be only programmed when link training the first LTTPR and kept
as-is when training subsequent LTTPRs and the DPRX. For these latter
PHYs the vs/pe levels will be set in response to writing the
DP_TRAINING_LANEx_SET_PHY_REPEATERy DPCD registers (by an upstream LTTPR
TX PHY snooping this write access of its downstream LTTPR/DPRX RX PHY).
The above is also described in DP Standard v2.0 under 3.6.6.1.
While at it simplify and add the LTTPR that is link trained to the debug
message in intel_dp_set_signal_levels().
Fixes: b30edfd8d0 ("drm/i915: Switch to LTTPR non-transparent mode link training")
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201229172201.4155327-2-imre.deak@intel.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.