6b24a0cac5
A transfer described by more than one TRB can reach the end of the ring
part way through, so the link that sends the controller back to the
beginning falls inside the transfer rather than between two of them.
Written without the chain bit, that link ends the transfer where it
stands: the controller follows it, considers the work finished, and
reports nothing, because the TRB that asked for the completion interrupt
is on the far side of the join. Nothing waiting is woken, and transfers
have no timeout, so the symptom is a read that never returns.
Carry the chain bit onto the link when the TRB it follows has it.
Reading 1MiB from a USB drive, where the last two sizes did not complete
at all before:
512 byte blocks 166 KB/s
4 KiB blocks 1333 KB/s
32 KiB blocks 10666 KB/s
64 KiB blocks 15515 KB/s
Assisted-by: Claude:claude-opus-5
Signed-off-by: Justin Hammond <justin@dynam.ac>
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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 | ||
| .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.