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Luca Ceresoli ac9de7b29e Revert "drm/bridge: ti-sn65dsi83: Fix enable error path" 
[ Upstream commit ad81feb5b6 ]

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
(cherry picked from commit 2940ee03b2)
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-06-12 11:03:48 +02:00
arch um: Fix the declaration of kasan_map_memory 2024-06-12 11:03:48 +02:00
block block: support to account io_ticks precisely 2024-06-12 11:03:07 +02:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto KEYS: asymmetric: Add missing dependencies of FIPS_SIGNATURE_SELFTEST 2024-06-12 11:02:58 +02:00
Documentation dt-bindings: pinctrl: mediatek: mt7622: fix array properties 2024-06-12 11:03:39 +02:00
drivers Revert "drm/bridge: ti-sn65dsi83: Fix enable error path" 2024-06-12 11:03:48 +02:00
fs fs/ntfs3: Use variable length array instead of fixed size 2024-06-12 11:03:46 +02:00
include media: cec: core: avoid recursive cec_claim_log_addrs 2024-06-12 11:03:48 +02:00
init rust: make mutually exclusive with CFI_CLANG 2024-05-02 16:29:27 +02:00
io_uring io_uring: use the right type for work_llist empty check 2024-06-12 11:03:05 +02:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel sched/core: Fix incorrect initialization of the 'burst' parameter in cpu_max_write() 2024-06-12 11:03:33 +02:00
lib lib/test_hmm.c: handle src_pfns and dst_pfns allocation failure 2024-06-12 11:03:29 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm/hugetlb: fix DEBUG_LOCKS_WARN_ON(1) when dissolve_free_hugetlb_folio() 2024-05-17 11:56:24 +02:00
net af_packet: do not call packet_read_pending() from tpacket_destruct_skb() 2024-06-12 11:03:32 +02:00
rust rust: macros: fix soundness issue in module! macro 2024-05-17 11:56:17 +02:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-23 09:12:28 +01:00
scripts btf, scripts: rust: drop is_rust_module.sh 2024-05-17 11:56:17 +02:00
security KEYS: trusted: Do not use WARN when encode fails 2024-05-25 16:21:35 +02:00
sound ASoC: Intel: avs: Fix potential integer overflow 2024-06-12 11:03:23 +02:00
tools perf stat: Don't display metric header for non-leader uncore events 2024-06-12 11:03:43 +02:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Always flush async #PF workqueue when vCPU is being destroyed 2024-04-03 15:19:25 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.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: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
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: add leah to 6.1 MAINTAINERS file 2024-05-17 11:56:16 +02:00
Makefile Linux 6.1.92 2024-05-25 16:21:36 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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 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.