The completion handler did:
dmach->callback(...);
dmach->callback = NULL; /* after the call */
so a callback that registers itself again -- which is the only way for a
driver to keep a channel running continuously -- has that registration
wiped the moment it returns. The channel transfers one more block and
then goes deaf, with no error raised anywhere and nothing in the
registers to say why. A PWM audio driver hit this and worked around it
by restarting from a thread instead, which put a millisecond of silence
into every buffer boundary.
Lift the callback and its argument out first and clear them before the
call. One-shot behaviour is unchanged for every existing user, since
none of them re-register from inside the call; the difference is only
that one which does now survives.
Tested on a Pimoroni Pico Plus 2 W (pimoroni-pico-plus-2-w:nsh) with a
local test: a memory-to-memory transfer whose callback starts the next
one, 100 times. Master gives 1 completion of 100; this change gives 100.
The existing users (SPI, I2S, CYW43439, WS2812) do not start a transfer
from inside the callback, so they do not change.
Assisted-by: Claude Code:claude-opus-5-5
Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com>
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| .github | ||
| arch | ||
| audio | ||
| binfmt | ||
| boards | ||
| cmake | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| dummy | ||
| fs | ||
| graphics | ||
| include | ||
| libs | ||
| mm | ||
| net | ||
| openamp | ||
| pass1 | ||
| sched | ||
| syscall | ||
| tools | ||
| video | ||
| wireless | ||
| .asf.yaml | ||
| .codespell-ignore-lines | ||
| .codespellrc | ||
| .editorconfig | ||
| .gitignore | ||
| .gitmessage | ||
| .mcp.json | ||
| .pre-commit-config.yaml | ||
| .yamllint | ||
| AUTHORS | ||
| CMakeLists.txt | ||
| CONTRIBUTING.md | ||
| INVIOLABLES.md | ||
| Kconfig | ||
| LICENSE | ||
| Makefile | ||
| NOTICE | ||
| README.md | ||
| ReleaseNotes | ||
Apache NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. Scalable from 8-bit to 64-bit microcontroller environments, the primary governing standards in NuttX are POSIX and ANSI standards. Additional standard APIs from Unix and other common RTOSs (such as VxWorks) are adopted for functionality not available under these standards, or for functionality that is not appropriate for deeply-embedded environments (such as fork()).
For brevity, many parts of the documentation will refer to Apache NuttX as simply NuttX.
Getting Started
First time on NuttX? Read the Getting Started guide! If you don't have a board available, NuttX has its own simulator that you can run on terminal.
Documentation
You can find the current NuttX documentation on the Documentation Page.
Alternatively, you can build the documentation yourself by following the Documentation Build Instructions.
The old NuttX documentation is still available in the Apache wiki.
Supported Boards
NuttX supports a wide variety of platforms. See the full list on the Supported Platforms page.
Contributing
If you wish to contribute to the NuttX project, read the Contributing guidelines for information on Git usage, coding standard, workflow and the NuttX principles.
License
The code in this repository is under either the Apache 2 license, or a license compatible with the Apache 2 license. See the License Page for more information.