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2940ee03b2
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Luca Ceresoli 2940ee03b2
Revert "drm/bridge: ti-sn65dsi83: Fix enable error path" 
This reverts commit 8a91b29f1f.

The regulator_disable() added by the original commit solves one kind of
regulator imbalance but adds another one as it allows the regulator to be
disabled one more time than it is enabled in the following scenario:

 1. Start video pipeline -> sn65dsi83_atomic_pre_enable -> regulator_enable
 2. PLL lock fails -> regulator_disable
 3. Stop video pipeline -> sn65dsi83_atomic_disable -> regulator_disable

The reason is clear from the code flow, which looks like this (after
removing unrelated code):

  static void sn65dsi83_atomic_pre_enable()
  {
      regulator_enable(ctx->vcc);

      if (PLL failed locking) {
          regulator_disable(ctx->vcc);  <---- added by patch being reverted
          return;
      }
  }

  static void sn65dsi83_atomic_disable()
  {
      regulator_disable(ctx->vcc);
  }

The use case for introducing the additional regulator_disable() was
removing the module for debugging (see link below for the discussion). If
the module is removed after a .atomic_pre_enable, i.e. with an active
pipeline from the DRM point of view, .atomic_disable is not called and thus
the regulator would not be disabled.

According to the discussion however there is no actual use case for
removing the module with an active pipeline, except for
debugging/development.

On the other hand, the occurrence of a PLL lock failure is possible due to
any physical reason (e.g. a temporary hardware failure for electrical
reasons) so handling it gracefully should be supported. As there is no way
for .atomic[_pre]_enable to report an error to the core, the only clean way
to support it is calling regulator_disabled() only in .atomic_disable,
unconditionally, as it was before.

Link: https://lore.kernel.org/all/15244220.uLZWGnKmhe@steina-w/
Fixes: 8a91b29f1f ("drm/bridge: ti-sn65dsi83: Fix enable error path")
Reviewed-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240426122259.46808-1-luca.ceresoli@bootlin.com
2024-04-29 12:24:58 +02:00
arch Linux 6.9-rc5 2024-04-22 14:35:52 +10:00
block block-6.9-20240420 2024-04-20 11:28:02 -07:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto This push fixes a regression that broke iwd as well as a divide by 2024-03-25 10:48:23 -07:00
Documentation dt-bindings: display: bridge: tc358775: Add support for tc358765 2024-04-23 17:28:59 +02:00
drivers Revert "drm/bridge: ti-sn65dsi83: Fix enable error path" 2024-04-29 12:24:58 +02:00
fs Kernfs bugfix and documentation update for 6.9-rc5 2024-04-21 10:30:21 -07:00
include drm/print: drop include seq_file.h 2024-04-25 17:05:48 +03:00
init init/main.c: Fix potential static_command_line memory overflow 2024-04-13 00:59:36 +09:00
io_uring io_uring/net: restore msg_control on sendzc retry 2024-04-08 21:48:41 -06:00
ipc sysctl changes for v6.9-rc1 2024-03-18 14:59:13 -07:00
kernel - Add a missing memory barrier in the concurrency ID mm switching 2024-04-21 09:39:36 -07:00
lib hardening fixes for v6.9-rc5 2024-04-19 14:10:11 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/shmem: inline shmem_is_huge() for disabled transparent hugepages 2024-04-16 15:39:51 -07:00
net netfilter pull request 24-04-18 2024-04-18 13:12:37 +02:00
rust Kbuild updates for v6.9 2024-03-21 14:41:00 -07:00
samples Tracing updates for 6.9: 2024-03-18 15:11:44 -07:00
scripts hardening fixes for v6.9-rc4 2024-04-10 13:31:34 -07:00
security security: Place security_path_post_mknod() where the original IMA call was 2024-04-03 10:21:32 -07:00
sound ALSA: seq: ump: Fix conversion from MIDI2 to MIDI1 UMP messages 2024-04-19 12:07:14 +02:00
tools * Clean up SVM's enter/exit assembly code so that it can be compiled 2024-04-20 11:10:51 -07:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt KVM: Drop unused @may_block param from gfn_to_pfn_cache_invalidate_start() 2024-04-11 12:58:53 -07:00
.clang-format clang-format: Update with v6.7-rc4's for_each macro list 2023-12-08 23:54:38 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: create a list of all built DTB files 2024-02-19 18:20:39 +09:00
.mailmap TTY/Serial driver fixes for 6.9-rc5 2024-04-21 10:27:01 -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 MAINTAINERS: Drop Gustavo Pimentel as PCI DWC Maintainer 2024-03-27 13:41:02 -05:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: fix LG sw43408 panel driver drm-misc git URL 2024-04-26 06:05:12 +03:00
Makefile Linux 6.9-rc5 2024-04-21 12:35:54 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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 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.