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Imre Deak 80a8cecf62 drm/i915/dp_mst: Disable link training fallback on MST links
During the initial probing of an MST sink, MST core will determine the
sink's link bandwidth based on its own version of the sink link
rate/lane count caps it reads from the DPCD. At a later point (after
probing and 1 or more modesets) i915 may limit the link parameters wrt.
the original source/sink common caps above due to link training failures
during a modeset and the resulting link training fallback logic.

Based on the above a modeset following another modeset with a link
training error will compute the i915 HW specific and DP protocol timing
parameters (data/link M/N and MST TU values) taking into account only
the unlimited source/sink common caps, but not taking into account the
fallback limits. This will also let DRM core oversubscribe the actual
link bandwidth during the MST payload allocation.

Prevent the above problem by disabling the link training fallback on MST
links for now, until the MST probe time initialization and the MST
compute config logic can deal with changing link parameters.

The misconfigured timings lead at least to a
'Timed out waiting for DP idle patterns'
error.

v2: (Ville)
- Print link training error message on the MST path too.
- Clarify the problem in the commit log.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Manasi Navare <manasi.d.navare@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/20200616211146.23027-2-imre.deak@intel.com
2020-06-23 10:12:13 +03:00
arch x86/gpu: add RKL stolen memory support 2020-05-20 08:35:22 -07:00
block block-5.7-2020-04-10 2020-04-10 10:06:54 -07:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto x86: update AS_* macros to binutils >=2.23, supporting ADX and AVX2 2020-04-09 00:12:48 +09:00
Documentation drm/i915: Document locking guidelines 2020-05-14 20:24:54 +03:00
drivers drm/i915/dp_mst: Disable link training fallback on MST links 2020-06-23 10:12:13 +03:00
fs 10 smb fixes most RDMA (smbdirect) related, also add experimental support for swap over SMB3 mounts, and also adds fix which improves performance of signed connections 2020-04-12 09:41:01 -07:00
include drm/i915/rkl: Add RKL platform info and PCI ids 2020-05-19 17:12:22 -07:00
init Kbuild updates for v5.7 (2nd) 2020-04-11 09:46:12 -07:00
ipc ipc/util.c: sysvipc_find_ipc() should increase position index 2020-04-10 15:36:22 -07:00
kernel Time(keeping) updates: 2020-04-12 10:13:14 -07:00
lib Kbuild updates for v5.7 (2nd) 2020-04-11 09:46:12 -07:00
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mm Merge branch 'akpm' (patches from Andrew) 2020-04-10 17:57:48 -07:00
net Kbuild updates for v5.7 (2nd) 2020-04-11 09:46:12 -07:00
samples samples/hw_breakpoint: drop use of kallsyms_lookup_name() 2020-04-07 10:43:44 -07:00
scripts kbuild: add dummy toolchains to enable all cc-option etc. in Kconfig 2020-04-09 00:13:45 +09:00
security Keyrings fixes 2020-04-04 12:24:47 -07:00
sound sound fixes for 5.7-rc1 2020-04-10 12:27:06 -07:00
tools Kbuild updates for v5.7 (2nd) 2020-04-11 09:46:12 -07:00
usr kbuild: fix comment about missing include guard detection 2020-04-11 12:09:48 +09:00
virt KVM: Pass kvm_init()'s opaque param to additional arch funcs 2020-03-31 10:48:03 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2020-03-06 21:50:05 +01:00
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.gitignore .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
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CREDITS MAINTAINERS: Hand MIPS over to Thomas 2020-02-24 22:43:18 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
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Makefile Linux 5.7-rc1 2020-04-12 12:35:55 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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 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.