Imre Deak a5bcf8dde6 drm/i915/ddi: Don't rewrite DDI_BUF_CTL reg during DP link training
The value we program to DDI_BUF_CTL changes at the following places:
- At enabling/disabling the output to configure the port width etc, and
  to enable/disable the DDI BUF function.
- At the beginning/end of link re-training to disable/re-enable the DDI
  BUF function.
- On HSW/BDW/SKL to change the voltage swing/pre-emph levels.

Except of the above the value we program to the DDI_BUF_CTL register
(intel_dp->DP) doesn't change, so no need to reprogram the register when
changing the link training patterns (which is programmed via the
DP_TP_CTL register on DDI platforms).

v2:
- Fix the commit message wrt. voltage/pre-emph level values in
  intel_dp->DP. (Ville)

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/20200714153141.10280-2-imre.deak@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
2020-08-17 16:15:44 -04:00
2020-08-11 11:58:31 +10:00
2020-08-11 11:58:31 +10:00
2020-07-24 12:42:41 -07:00
2020-08-11 11:58:31 +10:00
2020-08-02 14:21:45 -07:00

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.
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