The DMA driver will turn off DMA if it hasn't been used for an amount of
time (to save power). The SDIO driver for cyw43 WLAN was not informing the
DMA driver that it was using DMA and there was a chance that the DMA would
turn off in the middle of an SDIO DMA transfer. The symptoms of this would
be printing of SDIO error messages and a failure to communicate with the
cyw43 WLAN module.
This commit fixes this issue by changing the SDIO driver to use the
dma_nohal_XXX API to initialise and start the DMA.
Signed-off-by: Damien George <damien@micropython.org>
This can now be selected by setting MICROPY_HW_SDIO_SDMMC, which defaults
to 1, ie SDMMC1. The pins can also be selected and default to the standard
C8/C9/C10/C11/C12/D2.
