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Aleksandrs Vinarskis 5a0436e92a drm/msm/dp: Introduce link training per-segment for LTTPRs
DisplayPort requires per-segment link training when LTTPR are switched
to non-transparent mode, starting with LTTPR closest to the source.
Only when each segment is trained individually, source can link train
to sink.

Implement per-segment link traning when LTTPR(s) are detected, to
support external docking stations. On higher level, changes are:

* Pass phy being trained down to all required helpers
* Run CR, EQ link training per phy
* Set voltage swing, pre-emphasis levels per phy

Since at least some LTTPRs (eg. Parade PS8830) do not correctly report
voltage-swing, pre-emphasis level 3 support, always assume level 3 is
supported. This is permitted under DP 2.1(a) section 3.6.7.2 stating
that LTTPR shall set its transmitter levels as close as possible to
those requested by the DPTX, if the DPTX sets the voltage swing or
pre-emphasis to a level that the LTTPR does not support. It shall be
noted that LTTPR’s level choosing is implementation-specific.

This ensures successful link training both when connected directly to
the monitor (single LTTPR onboard most X1E laptops) and via the docking
station (at least two LTTPRs).

Fixes: 72d0af4acc ("drm/msm/dp: Add support for LTTPR handling")
Tested-by: Jessica Zhang <quic_jesszhan@quicinc.com> # SA8775P
Tested-by: Johan Hovold <johan+linaro@kernel.org>
Tested-by: Rob Clark <robdclark@gmail.com>
Tested-by: Stefan Schmidt <stefan.schmidt@linaro.org>
Signed-off-by: Aleksandrs Vinarskis <alex.vinarskis@gmail.com>
Reviewed-by: Abel Vesa <abel.vesa@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/652305/
Link: https://lore.kernel.org/r/20250507230113.14270-5-alex.vinarskis@gmail.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
2025-05-12 19:18:49 +03:00
arch arm64: dts: qcom: x1e80100: Add OPPs up to Turbo L3 for GPU 2025-05-10 09:04:13 -07:00
block treewide: Switch/rename to timer_delete[_sync]() 2025-04-05 10:30:12 +02:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push fixes reverts the multibuffer hash testing as it is buggy. 2025-04-02 09:14:59 -07:00
Documentation dt-bindings: display/msm/hdmi: drop obsolete GPIOs from schema 2025-05-12 19:18:48 +03:00
drivers drm/msm/dp: Introduce link training per-segment for LTTPRs 2025-05-12 19:18:49 +03:00
fs Changes since last update: 2025-04-13 10:52:04 -07:00
include drm/panthor: Add driver IOCTL for setting BO labels 2025-04-23 10:35:35 +02:00
init Miscellaneous scheduler fixes/updates: 2025-04-06 10:44:58 -07:00
io_uring io_uring/kbuf: reject zero sized provided buffers 2025-04-07 07:51:23 -06:00
ipc treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
kernel tracing fixes for v6.15 2025-04-12 15:37:40 -07:00
lib vsprintf: Use %p4chR instead of %p4cn for reading data in reversed host ordering 2025-04-29 09:29:33 -04:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm Disable SLUB_TINY for build testing 2025-04-06 10:00:04 -07:00
net bpf-fixes 2025-04-12 12:48:10 -07:00
rust Kbuild updates for v6.15 2025-04-05 15:46:50 -07:00
samples treewide: Switch/rename to timer_delete[_sync]() 2025-04-05 10:30:12 +02:00
scripts lib/vsprintf: Add support for generic FourCCs by extending %p4cc 2025-04-21 10:18:30 -04:00
security mseal sysmap: kernel config and header change 2025-04-01 15:17:14 -07:00
sound soundwire fix for 6.15-rc1 2025-04-06 12:04:53 -07:00
tools memblock: fix build of memblock test 2025-04-13 07:11:33 -07:00
usr kbuild: hdrcheck: fix cross build with clang 2025-03-05 04:06:45 +09:00
virt ARM: 2025-04-08 13:47:55 -07:00
.clang-format drm/vkms: Allow to attach connectors and encoders 2025-03-07 10:58:28 +01:00
.clippy.toml rust: give Clippy the minimum supported Rust version 2025-01-10 00:17:25 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: Create intermediate vmlinux build with relocations preserved 2025-03-17 00:29:50 +09:00
.mailmap mailmap: add an entry for Nicolas Schier 2025-04-01 15:20:45 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS Including fixes from netfilter. 2025-04-04 09:15:35 -07:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS dt-bindings: opp: Add v2-qcom-adreno vendor bindings 2025-05-04 09:20:29 -07:00
Makefile Linux 6.15-rc2 2025-04-13 11:54:49 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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 reStructuredText 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.