unimore/kernel-hacking-2024-linux-steffo
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Linux kernel modifications for the Kernel Hacking exam
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Stephen Boyd a3ee9e0b57 drm/panel: boe-tv101wum-nl6: Ensure DSI writes succeed during disable 
The unprepare sequence has started to fail after moving to panel bridge
code in the msm drm driver (commit 007ac0262b ("drm/msm/dsi: switch to
DRM_PANEL_BRIDGE")). You'll see messages like this in the kernel logs:

   panel-boe-tv101wum-nl6 ae94000.dsi.0: failed to set panel off: -22

This is because boe_panel_enter_sleep_mode() needs an operating DSI link
to set the panel into sleep mode. Performing those writes in the
unprepare phase of bridge ops is too late, because the link has already
been torn down by the DSI controller in post_disable, i.e. the PHY has
been disabled, etc. See dsi_mgr_bridge_post_disable() for more details
on the DSI .

Split the unprepare function into a disable part and an unprepare part.
For now, just the DSI writes to enter sleep mode are put in the disable
function. This fixes the panel off routine and keeps the panel happy.

My Wormdingler has an integrated touchscreen that stops responding to
touch if the panel is only half disabled too. This patch fixes it. And
finally, this saves power when the screen is off because without this
fix the regulators for the panel are left enabled when nothing is being
displayed on the screen.

Fixes: 007ac0262b ("drm/msm/dsi: switch to DRM_PANEL_BRIDGE")
Fixes: a869b9db7a ("drm/panel: support for boe tv101wum-nl6 wuxga dsi video mode panel")
Cc: yangcong <yangcong5@huaqin.corp-partner.google.com>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Jitao Shi <jitao.shi@mediatek.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Rob Clark <robdclark@chromium.org>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230106030108.2542081-1-swboyd@chromium.org
(cherry picked from commit c913cd5489)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
2023-02-01 11:41:15 +01:00
arch - Pass only an initialized perf event attribute to the LSM hook 2023-01-01 11:27:00 -08:00
block block-6.2-2022-12-29 2022-12-29 16:57:29 -08:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto This update includes the following changes: 2022-12-14 12:31:09 -08:00
Documentation block-6.2-2022-12-29 2022-12-29 16:57:29 -08:00
drivers drm/panel: boe-tv101wum-nl6: Ensure DSI writes succeed during disable 2023-02-01 11:41:15 +01:00
fs treewide: Convert del_timer*() to timer_shutdown*() 2022-12-25 13:38:09 -08:00
include drm/fb-helper: Use a per-driver FB deferred I/O handler 2023-01-24 11:13:08 +01:00
init Kbuild updates for v6.2 2022-12-19 12:33:32 -06:00
io_uring io_uring: check for valid register opcode earlier 2022-12-23 06:40:32 -07:00
ipc Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -08:00
kernel - Pass only an initialized perf event attribute to the LSM hook 2023-01-01 11:27:00 -08:00
lib kunit: alloc_string_stream_fragment error handling bug fix 2022-12-26 16:01:36 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm hugetlb: really allocate vma lock for all sharable vmas 2022-12-21 14:31:52 -08:00
net treewide: Convert del_timer*() to timer_shutdown*() 2022-12-25 13:38:09 -08:00
rust rust: types: add Opaque type 2022-12-04 01:59:16 +01:00
samples Char/Misc driver changes for 6.2-rc1 2022-12-16 03:49:24 -08:00
scripts fixdep: remove unneeded <stdarg.h> inclusion 2022-12-30 17:26:19 +09:00
security kernel hardening fixes for v6.2-rc1 2022-12-23 12:00:24 -08:00
sound ALSA: hda/hdmi: Static PCM mapping again with AMD HDMI codecs 2022-12-28 14:05:06 +01:00
tools Merge branch 'kvm-late-6.1-fixes' into HEAD 2022-12-28 07:19:14 -05:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt Merge branch 'kvm-late-6.1-fixes' into HEAD 2022-12-28 07:19:14 -05:00
.clang-format iommufd for 6.2 2022-12-14 09:15:43 -08:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore .gitignore: ignore *.rpm 2022-12-30 17:22:14 +09:00
.mailmap Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS MAINTAINERS: zram: zsmalloc: Add an additional co-maintainer 2022-12-15 16:37:49 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
MAINTAINERS block-6.2-2022-12-29 2022-12-29 16:57:29 -08:00
Makefile Linux 6.2-rc2 2023-01-01 13:53:16 -08:00
README

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.