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Filename Latest commit message Latest commit date
Mathias Nyman b25dad547b usb: hub: Don't try to recover devices lost during warm reset.
[ Upstream commit 2521106fc732b0b75fd3555c689b1ed1d29d273c ]

Hub driver warm-resets ports in SS.Inactive or Compliance mode to
recover a possible connected device. The port reset code correctly
detects if a connection is lost during reset, but hub driver
port_event() fails to take this into account in some cases.
port_event() ends up using stale values and assumes there is a
connected device, and will try all means to recover it, including
power-cycling the port.

Details:
This case was triggered when xHC host was suspended with DbC (Debug
Capability) enabled and connected. DbC turns one xHC port into a simple
usb debug device, allowing debugging a system with an A-to-A USB debug
cable.

xhci DbC code disables DbC when xHC is system suspended to D3, and
enables it back during resume.
We essentially end up with two hosts connected to each other during
suspend, and, for a short while during resume, until DbC is enabled back.
The suspended xHC host notices some activity on the roothub port, but
can't train the link due to being suspended, so xHC hardware sets a CAS
(Cold Attach Status) flag for this port to inform xhci host driver that
the port needs to be warm reset once xHC resumes.

CAS is xHCI specific, and not part of USB specification, so xhci driver
tells usb core that the port has a connection and link is in compliance
mode. Recovery from complinace mode is similar to CAS recovery.

xhci CAS driver support that fakes a compliance mode connection was added
in commit 8bea2bd37d ("usb: Add support for root hub port status CAS")

Once xHCI resumes and DbC is enabled back, all activity on the xHC
roothub host side port disappears. The hub driver will anyway think
port has a connection and link is in compliance mode, and hub driver
will try to recover it.

The port power-cycle during recovery seems to cause issues to the active
DbC connection.

Fix this by clearing connect_change flag if hub_port_reset() returns
-ENOTCONN, thus avoiding the whole unnecessary port recovery and
initialization attempt.

Cc: stable@vger.kernel.org
Fixes: 8bea2bd37d ("usb: Add support for root hub port status CAS")
Tested-by: Łukasz Bartosik <ukaszb@chromium.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20250623133947.3144608-1-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-08-28 16:21:34 +02:00
arch x86/mce/amd: Add default names for MCA banks and blocks 2025-08-28 16:21:34 +02:00
block block: fix 'kmem_cache of name 'bio-108' already exists' 2025-04-10 14:29:37 +02:00
certs
crypto crypto: algif_hash - fix double free in hash_accept 2025-06-04 14:32:35 +02:00
Documentation Documentation: ACPI: Fix parent device references 2025-08-28 16:21:23 +02:00
drivers usb: hub: Don't try to recover devices lost during warm reset. 2025-08-28 16:21:34 +02:00
fs f2fs: fix to do sanity check on ino and xnid 2025-08-28 16:21:33 +02:00
include net: usbnet: Avoid potential RCU stall on LINK_CHANGE event 2025-08-28 16:21:33 +02:00
init bpfilter: match bit size of bpfilter_umh to that of the kernel 2025-07-17 18:24:51 +02:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:02:52 +01:00
kernel ftrace: Also allocate and copy hash for reading of filter files 2025-08-28 16:21:32 +02:00
lib lib: test_objagg: Set error message in check_expect_hints_stats() 2025-07-17 18:24:56 +02:00
LICENSES
mm mm/zsmalloc: do not pass __GFP_MOVABLE if CONFIG_COMPACTION=n 2025-08-28 16:21:33 +02:00
net net: ncsi: Fix buffer overflow in fetching version id 2025-08-28 16:21:27 +02:00
samples samples: mei: Fix building on musl libc 2025-08-28 16:21:19 +02:00
scripts kbuild: Add KBUILD_CPPFLAGS to as-option invocation 2025-08-28 16:21:33 +02:00
security securityfs: don't pin dentries twice, once is enough... 2025-08-28 16:21:24 +02:00
sound ASoC: codecs: rt5640: Retry DEVICE_ID verification 2025-08-28 16:21:26 +02:00
tools ktest.pl: Prevent recursion of default variable options 2025-08-28 16:21:26 +02:00
usr kbuild: hdrcheck: fix cross build with clang 2025-07-17 18:24:51 +02:00
virt KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status 2024-12-19 18:05:04 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Remove *.orig pattern from .gitignore 2024-11-08 16:20:33 +01:00
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS platform: Add Surface platform directory 2025-06-27 11:02:56 +01:00
Makefile kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS 2025-08-28 16:21:33 +02:00
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.