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RIOT/cpu/sam0_common/periph/Kconfig.spi
Benjamin Valentin 669104d841 cpu/sam0_common: SPI: don't perform DMA transfer for small buffers
Setting up a DMA transfer can take longer than sending out a buffer
byte by byte if the buffer is small.

DMA only shows advantages for large buffers, using it for every transfer
will cause a net slowdown.

Since we did not come up with a good way to determine the treshold based
on the SPI frequency, just use a fixed buffer for now so that DMA can be
used without slowing things down overall.
2021-11-19 17:22:51 +01:00

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# Copyright (c) 2020 HAW Hamburg
#
# This file is subject to the terms and conditions of the GNU Lesser
# General Public License v2.1. See the file LICENSE in the top level
# directory for more details.
config SPI_DMA_THRESHOLD_BYTES
int "SPI DMA threshold (bytes)"
depends on MODULE_PERIPH_DMA
depends on MODULE_PERIPH_SPI
default 16
help
Threshold in bytes under which no SPI DMA transfer will be performed.
Polling will be used instead.