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Nícolas F. R. A. Prado 376daf3aa8 drm/bridge: anx7625: Prevent endless probe loop 
[ Upstream commit 1464e48d69 ]

During probe, the driver registers i2c dummy devices and populates the
aux bus, which registers a device for the panel. After doing that, the
driver can still defer probe if needed. This ordering of operations is
troublesome however, because the deferred probe work will retry probing
all pending devices every time a new device is registered. Therefore, if
modules need to be loaded in order to satisfy the dependencies for this
driver to complete probe, the kernel will stall, since it'll keep trying
to probe the anx7625 driver, but never succeed, given that modules would
only be loaded after the deferred probe work completes.

Two changes are required to avoid this issue:
* Move of_find_mipi_dsi_host_by_node(), which can defer probe, to before
  anx7625_register_i2c_dummy_clients() and
  devm_of_dp_aux_populate_ep_devices(), which register devices.
* Make use of the done_probing callback when populating the aux bus,
  so that the bridge registration is only done after the panel is
  probed. This is required because the panel might need to defer probe,
  but the aux bus population needs the i2c dummy devices working, so
  this call couldn't just be moved to an earlier point in probe.
  One caveat is that if the panel is described outside the aux bus, the
  probe loop issue can still happen, but we don't have a way to avoid
  it in that case since there's no callback available.

With this patch applied, it's possible to boot on
mt8192-asurada-spherion with

CONFIG_DRM_ANALOGIX_ANX7625=y
CONFIG_MTK_MMSYS=m
CONFIG_BACKLIGHT_PWM=y

and also with

CONFIG_DRM_ANALOGIX_ANX7625=y
CONFIG_MTK_MMSYS=y
CONFIG_BACKLIGHT_PWM=m

Fixes: adca62ec37 ("drm/bridge: anx7625: Support reading edid through aux channel")
Fixes: 269332997a ("drm/bridge: anx7625: Return -EPROBE_DEFER if the dsi host was not found")
Reported-by: "kernelci.org bot" <bot@kernelci.org>
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230518193902.891121-1-nfraprado@collabora.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2023-07-19 16:21:21 +02:00
arch ARM: dts: gta04: Move model property out of pinctrl node 2023-07-19 16:21:21 +02:00
block block: fix blktrace debugfs entries leakage 2023-07-19 16:20:58 +02:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto KEYS: asymmetric: Copy sig and digest in public_key_verify_signature() 2023-06-09 10:34:28 +02:00
Documentation docs: Set minimal gtags / GNU GLOBAL version to 6.6.5 2023-07-05 18:27:38 +01:00
drivers drm/bridge: anx7625: Prevent endless probe loop 2023-07-19 16:21:21 +02:00
fs ocfs2: Fix use of slab data with sendpage 2023-07-19 16:21:13 +02:00
include drm: Add fixed-point helper to get rounded integer values 2023-07-19 16:21:18 +02:00
init gcc: disable '-Warray-bounds' for gcc-13 too 2023-04-26 14:28:43 +02:00
io_uring io_uring/net: use the correct msghdr union member in io_sendmsg_copy_hdr 2023-06-28 11:12:33 +02:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel kexec: fix a memory leak in crash_shrink_memory() 2023-07-19 16:21:08 +02:00
lib lib/ts_bm: reset initial match offset for every block of text 2023-07-19 16:21:13 +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: call arch_swap_restore() from do_swap_page() 2023-07-19 16:21:16 +02:00
net netlink: Add __sock_i_ino() for __netlink_diag_dump(). 2023-07-19 16:21:13 +02:00
rust rust: kernel: Mark rust_fmt_argument as extern "C" 2023-04-26 14:28:38 +02:00
samples samples/bpf: xdp1 and xdp2 reduce XDPBUFSIZE to 60 2023-07-19 16:21:07 +02:00
scripts scripts/tags.sh: Resolve gtags empty index generation 2023-07-05 18:27:38 +01:00
security ima: Fix build warnings 2023-07-19 16:21:03 +02:00
sound ASoC: Intel: sof_sdw: remove SOF_SDW_TGL_HDMI for MeteorLake devices 2023-07-19 16:21:18 +02:00
tools selftests: rtnetlink: remove netdevsim device after ipsec offload test 2023-07-19 16:21:12 +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: Avoid illegal stage2 mapping on invalid memory slot 2023-06-28 11:12:23 +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 smb: move client and server files to common directory fs/smb 2023-06-28 11:12:40 +02:00
Makefile Linux 6.1.38 2023-07-05 18:27:38 +01:00
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.