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Tomi Valkeinen daf57c5ce1 drm/mipi-dsi: Fix detach call without attach 
[ Upstream commit 90d50b8d85 ]

It's been reported that DSI host driver's detach can be called without
the attach ever happening:

https://lore.kernel.org/all/20230412073954.20601-1-tony@atomide.com/

After reading the code, I think this is what happens:

We have a DSI host defined in the device tree and a DSI peripheral under
that host (i.e. an i2c device using the DSI as data bus doesn't exhibit
this behavior).

The host driver calls mipi_dsi_host_register(), which causes (via a few
functions) mipi_dsi_device_add() to be called for the DSI peripheral. So
now we have a DSI device under the host, but attach hasn't been called.

Normally the probing of the devices continues, and eventually the DSI
peripheral's driver will call mipi_dsi_attach(), attaching the
peripheral.

However, if the host driver's probe encounters an error after calling
mipi_dsi_host_register(), and before the peripheral has called
mipi_dsi_attach(), the host driver will do cleanups and return an error
from its probe function. The cleanups include calling
mipi_dsi_host_unregister().

mipi_dsi_host_unregister() will call two functions for all its DSI
peripheral devices: mipi_dsi_detach() and mipi_dsi_device_unregister().
The latter makes sense, as the device exists, but the former may be
wrong as attach has not necessarily been done.

To fix this, track the attached state of the peripheral, and only detach
from mipi_dsi_host_unregister() if the peripheral was attached.

Note that I have only tested this with a board with an i2c DSI
peripheral, not with a "pure" DSI peripheral.

However, slightly related, the unregister machinery still seems broken.
E.g. if the DSI host driver is unbound, it'll detach and unregister the
DSI peripherals. After that, when the DSI peripheral driver unbound
it'll call detach either directly or using the devm variant, leading to
a crash. And probably the driver will crash if it happens, for some
reason, to try to send a message via the DSI bus.

But that's another topic.

Tested-by: H. Nikolaus Schaller <hns@goldelico.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230921-dsi-detach-fix-v1-1-d0de2d1621d9@ideasonboard.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-02-05 20:14:27 +00:00
arch arm64: dts: sprd: Change UMS512 idle-state nodename to match bindings 2024-02-05 20:14:25 +00:00
block block: prevent an integer overflow in bvec_try_merge_hw_page 2024-02-05 20:14:24 +00:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: api - Disallow identical driver names 2024-01-31 16:18:49 -08:00
Documentation ASoC: doc: Fix undefined SND_SOC_DAPM_NOPM argument 2024-02-05 20:14:26 +00:00
drivers drm/mipi-dsi: Fix detach call without attach 2024-02-05 20:14:27 +00:00
fs f2fs: fix write pointers on zoned device after roll forward 2024-02-05 20:14:26 +00:00
include drm/mipi-dsi: Fix detach call without attach 2024-02-05 20:14:27 +00:00
init rootfs: Fix support for rootfstype= when root= is given 2024-01-25 15:35:46 -08:00
io_uring io_uring: adjust defer tw counting 2024-01-25 15:36:00 -08:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel bpf: Set uattr->batch.count as zero before batched update or deletion 2024-02-05 20:14:21 +00:00
lib debugobjects: Stop accessing objects after releasing hash bucket lock 2024-02-05 20:14:14 +00:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm memblock: fix crash when reserved memory is not added to memory 2024-01-31 16:19:12 -08:00
net net: kcm: fix direct access to bv_len 2024-02-05 20:14:25 +00:00
rust rust: Ignore preserve-most functions 2024-01-25 15:35:41 -08:00
samples vfio/mtty: Overhaul mtty interrupt handling 2024-01-10 17:16:55 +01:00
scripts scripts/get_abi: fix source path leak 2024-01-31 16:18:55 -08:00
security lsm: new security_file_ioctl_compat() hook 2024-01-31 16:18:54 -08:00
sound ASoC: amd: Add new dmi entries for acp5x platform 2024-02-05 20:14:26 +00:00
tools libbpf: Fix NULL pointer dereference in bpf_object__collect_prog_relos 2024-02-05 20:14:24 +00:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt ARM: 2023-09-07 13:52:20 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.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: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.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 USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
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 Char/Misc driver fixes for 6.6-final 2023-10-28 07:51:27 -10:00
Makefile Linux 6.6.15 2024-01-31 16:19:14 -08:00
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.