pbarada opened a new pull request, #21093:
URL: https://github.com/apache/nuttx/pull/21093
## Summary
Add CONFIG_STM32_SDMMC1/2_SD_HS_MODE which if enabled (and corresponding
STM32_SDMMC_SDXFR_HS_CLKDIV is defined in board.h) then after generic MMC/SD
driver switches to 4-bit mode and card supports high-speed, then increase SD
clk from 25Mhz to 50Mhz.
## Impact
- User experience: No adaptation required. This fix extends functionality.
- Build: No impact.
- Hardware: Affects stm32h7 based-boards that enable SDMMC
- Documentation: No impact.
- Security: No impact.
- Compatibility: Backward compatible
Note this change (by itself) does not change code execution since
STM32_SDMMC1/2_HS_MODE Kconfig option needs to be enabled, and if so then also
STM32_SDMMC_SDXFR_HS_CLKDIV needs to be set to the divisor
required to clock to 50Mhz.
## Testing
Build Host:
- OS: Ubuntu 24.04.4 LTS
- Compiler: arm-none-eabi-gcc 13.2.1
Target:
- Architecture: ARM (STM32H7S3L8)
- Build tested for all stm32h7 configurations that enable STM32_SDMMC1:
stm32f746-ws:nsh, linum-stm32h753bi:nxdoom, linum-stm32h753bi:usbmsc-sdcard,
linum-stm32h753bi:zmodem, linum-stm32h753bi:sdcard,
linum-stm32h753bi:lvglterm_kbda, linum-stm32h753bi:curl,
devebox-stm32h743:full, weact-stm32h743:sdcard,
openh743i:composite_fs, openh743i:composite_hs,
weact-stm32h750:sdcard).
Further, used this change in a not yet submitted change to add SDMMC support
to stm32h7s8-dk, and on that board used a SparkFun SD sniffer and Saleae
analyzer to verify:
- CMD6 is issued with successuful response
- SD clk increases to 50Mhz
- Successful transfers.
From console of stm32h7s8-dk:
```
Bootloader 13.1.0 846e525657-dirty Oct 27 2026 18:22:33 arm stm32h7s8-dk
NuttShell (NSH) NuttX-13.1.0
NuttShell (NSH) NuttX-13.1.0
nsh> uname -a
NuttX 13.1.0 846e525657-dirty Oct 27 2026 18:22:35 arm stm32h7s8-dk
nsh> time "dd if=/dev/mmcsd0 of=/dev/null bs=4096 count=4096"
16777216 bytes (4096 blocks) copied, 1720000 usec, 9525 KB/s
1.7200 sec
nsh> mkdir /card
nsh> mount -t vfat /dev/mmcsd0 /card
nsh> ls /card
/card:
Garmin/
nsh> ls -l /card/Garmin
/card/Garmin:
-rwxrwxrwx 9763 GarminDevice.xml
drwxrwxrwx 0 UserData/
nsh>
```
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