ec9891c03a
Two sequencing problems in the MMC wide bus path break eMMC 4-bit operation on hosts that program the bus width in the SDIO widebus / clock callbacks (e.g. STM32H7): 1. The SWITCH command (CMD6) is issued before the host has switched to wide bus operation. When the card completes the switch while the host is still in 1-bit mode the switch never takes effect and every following data transfer times out. Switch the host to wide bus operation before issuing CMD6. 2. The transfer clock is selected only at the end of mmcsd_widebus(), so the whole switch sequence runs at ID-mode clock and, on the affected hosts, the final clock update does not take effect either, leaving the bus at ~400 kHz. Select the MMC transfer clock before calling mmcsd_widebus(), and pick CLOCK_MMC_TRANSFER_4BIT when wide bus operation is active (mirroring the SD card path) so a later clock selection cannot revert the host to 1-bit. No behavior change for SD cards, and no change on hosts whose widebus callback only records the requested state. Tested on a custom STM32H743 board with eMMC: sd_bench sequential write ~4.1 MB/s, sequential read ~6.3 MB/s (previously all data transfers timed out). Signed-off-by: DuoYuWang <thirteenking.wang@gmail.com> |
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| 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.