3f3a9bc1f6
The spec requires to use at least 3.2ms for the AUX timeout period if there are LT-tunable PHY Repeaters on the link (2.11.2). An upcoming spec update makes this more specific, by requiring a 3.2ms minimum timeout period for the LTTPR detection reading the 0xF0000-0xF0007 range (3.6.5.1). Accordingly disable LTTPR detection until GLK, where the maximum timeout we can set is only 1.6ms. Link training in the non-transparent mode is known to fail at least on some SKL systems with a WD19 dock on the link, which exposes an LTTPR (see the References below). While this could have different reasons besides the too short AUX timeout used, not detecting LTTPRs (and so not using the non-transparent LT mode) fixes link training on these systems. While at it add a code comment about the platform specific maximum timeout values. v2: Add a comment about the g4x maximum timeout as well. (Ville) Reported-by: Takashi Iwai <tiwai@suse.de> Reported-and-tested-by: Santiago Zarate <santiago.zarate@suse.com> Reported-and-tested-by: Bodo Graumann <mail@bodograumann.de> References: https://gitlab.freedesktop.org/drm/intel/-/issues/3166 Fixes: b30edfd8d0b4 ("drm/i915: Switch to LTTPR non-transparent mode link training") Cc: <stable@vger.kernel.org> # v5.11 Cc: Takashi Iwai <tiwai@suse.de> 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/20210317184901.4029798-2-imre.deak@intel.com (cherry picked from commit 984982f3ef7b240cd24c2feb2762d81d9d8da3c2) Signed-off-by: Rodrigo Vivi <rodrigo.vivi@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.