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Filename Latest commit message Latest commit date
Guenter Roeck 54abe030df i2c: smbus: Improve handling of stuck alerts
[ Upstream commit 37c526f00bc1c4f847fc800085f8f009d2e11be6 ]

The following messages were observed while testing alert functionality
on systems with multiple I2C devices on a single bus if alert was active
on more than one chip.

smbus_alert 3-000c: SMBALERT# from dev 0x0c, flag 0
smbus_alert 3-000c: no driver alert()!

and:

smbus_alert 3-000c: SMBALERT# from dev 0x28, flag 0

Once it starts, this message repeats forever at high rate. There is no
device at any of the reported addresses.

Analysis shows that this is seen if multiple devices have the alert pin
active. Apparently some devices do not support SMBus arbitration correctly.
They keep sending address bits after detecting an address collision and
handle the collision not at all or too late.
Specifically, address 0x0c is seen with ADT7461A at address 0x4c and
ADM1021 at address 0x18 if alert is active on both chips. Address 0x28 is
seen with ADT7483 at address 0x2a and ADT7461 at address 0x4c if alert is
active on both chips.

Once the system is in bad state (alert is set by more than one chip),
it often only recovers by power cycling.

To reduce the impact of this problem, abort the endless loop in
smbus_alert() if the same address is read more than once and not
handled by a driver.

Fixes: b5527a7766 ("i2c: Add SMBus alert support")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
[wsa: it also fixed an interrupt storm in one of my experiments]
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
[wsa: rebased, moved a comment as well, improved the 'invalid' value]
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-08-19 05:33:50 +02:00
arch arm64: errata: Expand speculative SSBS workaround (again) 2024-08-19 05:33:50 +02:00
block block: prevent division by zero in blk_rq_stat_sum() 2024-04-13 12:51:38 +02:00
certs
crypto crypto: ecrdsa - Fix module auto-load on add_key 2024-06-16 13:28:51 +02:00
Documentation arm64: errata: Expand speculative SSBS workaround (again) 2024-08-19 05:33:50 +02:00
drivers i2c: smbus: Improve handling of stuck alerts 2024-08-19 05:33:50 +02:00
fs ext4: fix wrong unit use in ext4_mb_find_by_goal 2024-08-19 05:33:48 +02:00
include PCI: Add Edimax Vendor ID to pci_ids.h 2024-08-19 05:33:47 +02:00
init init: open /initrd.image with O_LARGEFILE 2024-04-13 12:51:36 +02:00
ipc
kernel genirq: Allow irq_chip registration functions to take a const irq_chip 2024-08-19 05:33:45 +02:00
lib kobject_uevent: Fix OOB access within zap_modalias_env() 2024-08-19 05:33:38 +02:00
LICENSES
mm mm: avoid overflows in dirty throttling logic 2024-08-19 05:33:42 +02:00
net SUNRPC: Fix a race to wake a sync task 2024-08-19 05:33:48 +02:00
samples media: rename VFL_TYPE_GRABBER to _VIDEO 2024-03-26 18:22:22 -04:00
scripts kconfig: remove wrong expr_trans_bool() 2024-07-27 10:38:29 +02:00
security apparmor: Fix null pointer deref when receiving skb during sock creation 2024-08-19 05:33:42 +02:00
sound ALSA: usb-audio: Correct surround channels in UAC1 channel map 2024-08-19 05:33:45 +02:00
tools selftests/bpf: Fix send_signal test with nested CONFIG_PARAVIRT 2024-08-19 05:33:47 +02:00
usr
virt KVM: async_pf: Cleanup kvm_setup_async_pf() 2024-05-02 16:18:32 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS iio: stx104: Move to addac subdirectory 2023-08-30 16:27:12 +02:00
Makefile Linux 5.4.281 2024-07-27 10:38:33 +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.