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Mario Kleiner cb50813998 drm/amd/display: Only use depth 36 bpp linebuffers on DCN display engines.
Various DCE versions had trouble with 36 bpp lb depth, requiring fixes,
last time in commit 353ca0fa56 ("drm/amd/display: Fix 10bit 4K display
on CIK GPUs") for DCE-8. So far >= DCE-11.2 was considered ok, but now I
found out that on DCE-11.2 it causes dithering when there shouldn't be
any, so identity pixel passthrough with identity gamma LUTs doesn't work
when it should. This breaks various important neuroscience applications,
as reported to me by scientific users of Polaris cards under Ubuntu 22.04
with Linux 5.15, and confirmed by testing it myself on DCE-11.2.

Lets only use depth 36 for DCN engines, where my testing showed that it
is both necessary for high color precision output, e.g., RGBA16 fb's,
and not harmful, as far as more than one year in real-world use showed.

DCE engines seem to work fine for high precision output at 30 bpp, so
this ("famous last words") depth 30 should hopefully fix all known problems
without introducing new ones.

Successfully retested on DCE-11.2 Polaris and DCN-1.0 Raven Ridge on
top of Linux 5.19.0-rc2 + drm-next.

Fixes: 353ca0fa56 ("drm/amd/display: Fix 10bit 4K display on CIK GPUs")
Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Tested-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Cc: stable@vger.kernel.org # 5.14.0
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
2022-07-13 11:25:18 -04:00
arch Merge tag 'drm-intel-next-2022-05-06' of git://anongit.freedesktop.org/drm/drm-intel into drm-next 2022-05-11 11:00:15 +10:00
block bfq: Fix warning in bfqq_request_over_limit() 2022-04-29 06:45:37 -06:00
certs Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
crypto for-5.18/64bit-pi-2022-03-25 2022-03-26 12:01:35 -07:00
Documentation drm/amdgpu: Fix acronym typo in glossary 2022-07-13 11:25:18 -04:00
drivers drm/amd/display: Only use depth 36 bpp linebuffers on DCN display engines. 2022-07-13 11:25:18 -04:00
fs Driver core fixes for 5.18-rc5 2022-04-30 10:24:21 -07:00
include drm/amdkfd: bump KFD version for unified ctx save/restore memory 2022-07-12 16:50:44 -04:00
init Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
ipc fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
kernel Revert "workqueue: remove unused cancel_work()" 2022-06-10 15:24:38 -04:00
lib - A fix to disable PCI/MSI[-X] masking for XEN_HVM guests as that is 2022-05-01 10:03:36 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm kasan: prevent cpu_quarantine corruption when CPU offline and cache shrink occur at same time 2022-04-27 13:28:48 -07:00
net A fix for a NULL dereference that turns out to be easily triggerable 2022-04-29 14:37:35 -07:00
samples vfio/mdev: Remove mdev_parent_ops 2022-04-21 07:36:56 -04:00
scripts objtool: Enable unreachable warnings for CLANG LTO 2022-04-19 21:58:48 +02:00
security hardening updates for v5.18-rc1-fix1 2022-03-31 11:43:01 -07:00
sound ALSA: hda/realtek: Add quirk for Clevo NP70PNP 2022-04-21 21:23:47 +02:00
tools - A fix to disable PCI/MSI[-X] masking for XEN_HVM guests as that is 2022-05-01 10:03:36 -07:00
usr Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
virt Merge branch 'kvm-fixes-for-5.18-rc5' into HEAD 2022-04-29 12:39:34 -04:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: update Vasily Averin's email address 2022-04-08 14:20:36 -10:00
COPYING
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge tag 'drm-msm-next-2022-05-09' of https://gitlab.freedesktop.org/drm/msm into drm-next 2022-05-11 12:40:47 +10:00
Makefile Linux 5.18-rc5 2022-05-01 13:57:58 -07:00
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.