mainlining shenanigans
eddbb074ce
To avoid AUX timeouts and subsequent spurious hotplug interrupts, make
sure that the first DPCD access during detection is a read from an LTTPR
register.
Some ADLP DP link configuration at least with multiple LTTPRs expects
the first DPCD access during the LTTPR/DPCD detection after hotplug to
be a read from the LTTPR range starting with
DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV. The side effect of
this read is to put each LTTPR into the LTTPR transparent or LTTPR
non-transparent mode.
The lack of the above read may leave some of the LTTPRs in non-LTTPR
mode, while other LTTPRs in LTTPR transparent or LTTPR non-transparent
mode (for instance LTTPRs after system suspend/resume that kept their
mode from before suspend). Due to the different AUX timeouts the
different modes imply, the DPCD access from a non-LTTPR range will
timeout and lead to an LTTPR generated hotplug towards the source (which
the LTTPR firmware uses to account for buggy TypeC adapters with a long
wake-up delay).
SYSCROS: 72939
v2: Keep DPCD read-out working on non-LTTPR platforms.
v3: Summarize what and why the patch does at the beginning of the commit
log. (Jani)
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220408224629.845887-1-imre.deak@intel.com
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| certs | ||
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| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.