mirror of
https://github.com/torvalds/linux.git
synced 2026-07-31 11:37:06 +02:00
Linux kernel source tree
b5f871ab49
Some ath9k chips can, seemingly at random, end up in a state which can be described as "deaf". No or nearly no interrupts are generated anymore for incoming packets. Existing links either break down after a while and new links will not be established. The circumstances leading to this "deafness" is still unclear, but some particular chips (especially 2-stream 11n SoCs, but also others) can go 'deaf' when running AP or mesh (or both) after some time. It's probably a hardware issue, and doing a channel scan to trigger a chip reset (which one normally can't do on an AP interface) recovers the hardware. The only way the driver can detect this state, is by detecting if there has been no RX activity for a while. In this case we can proactively reset the chip (which only takes a small number of milliseconds, so shouldn't interrupt things too much if it has been idle for several seconds), which functions as a workaround. OpenWrt, and various derivatives, have been carrying versions of this workaround for years, that were never upstreamed. One version[0], written by Felix Fietkau, used a simple counter and only reset if there was precisely zero RX activity for a long period of time. This had the problem that in some cases a small number of interrupts would appear even if the device was otherwise not responsive. For this reason, another version[1], written by Simon Wunderlich and Sven Eckelmann, used a time-based approach to calculate the average number of RX interrupts over a longer (four-second) interval, and reset the chip when seeing less than one interrupt per second over this period. However, that version relied on debugfs counters to keep track of the number of interrupts, which means it didn't work at all if debugfs was not enabled. This patch unifies the two versions: it uses the same approach as Felix' patch to count the number of RX handler invocations, but uses the same time-based windowing approach as Simon and Sven's patch to still handle the case where occasional interrupts appear but the device is otherwise deaf. Since this is based on ideas by all three people, but not actually directly derived from any of the patches, I'm including Suggested-by tags from Simon, Sven and Felix below, which should hopefully serve as proper credit. [0] https://patchwork.kernel.org/project/linux-wireless/patch/20170125163654.66431-3-nbd@nbd.name/ [1] https://patchwork.kernel.org/project/linux-wireless/patch/20161117083614.19188-2-sven.eckelmann@open-mesh.com/ Suggested-by: Simon Wunderlich <sw@simonwunderlich.de> Suggested-by: Sven Eckelmann <se@simonwunderlich.de> Suggested-by: Felix Fietkau <nbd@nbd.name> Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk> Tested-by: Sven Eckelmann <se@simonwunderlich.de> Reviewed-by: Sven Eckelmann <se@simonwunderlich.de> Tested-by: Issam Hamdi <ih@simonwunderlich.de> Acked-by: Simon Wunderlich <sw@simonwunderlich.de> Link: https://patch.msgid.link/20241106-ath9k-deaf-detection-v1-1-736a150d2425@redhat.com Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com> |
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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 reStructuredText 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.