a85b28bc2c
rp2040_update_buffer_control()/rp23xx_update_buffer_control() re-arm an endpoint buffer by setting the AVAILABLE bit in the buffer-control word, which lives in DPSRAM. When a buffer is re-armed from the completion path (rp2040_usbintr_buffstat/rp23xx_usbintr_buffstat), that runs after the handler has cleared the endpoint's bit in BUFF_STATUS, which lives in the USB controller register block -- a different peripheral region. The bus fabric may reorder those two stores. If the controller observes the AVAILABLE re-arm before the BUFF_STATUS clear lands, it can transmit the next IN packet and latch its completion in BUFF_STATUS before the clear arrives; the late clear then wipes that just-set completion bit. The lost completion edge stops all further buffer interrupts for the endpoint, so the class driver's write-complete callback never runs and TX wedges permanently. This is most visible on RP2350 (Cortex-M33) under dense/bursty IN traffic such as CDC-NCM with TCP write buffers. Add a UP_DMB() at the top of the AVAILABLE re-arm so the preceding BUFF_STATUS clear is ordered ahead of it. (Non-SMP builds reduce spin_lock_irqsave to a barrier-free up_irq_save, so nothing else orders these two stores.) Assisted-by: Claude (Anthropic Claude Code) Signed-off-by: Ricard Rosson <ricard@groundbits.com> |
||
|---|---|---|
| .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 | ||
| .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.