diff options
| author | Patrice Chotard <patrice.chotard@foss.st.com> | 2021-04-19 15:15:40 +0300 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2021-04-19 16:18:43 +0300 |
| commit | f3530f26f8e9869e6e8c3370cf6f61330774fe2b (patch) | |
| tree | 6649974505754d1e73b965cd5e0dc18dd73dc599 /drivers/spi | |
| parent | 102e9d1936569d43f55dd1ea89be355ad207143c (diff) | |
| download | linux-f3530f26f8e9869e6e8c3370cf6f61330774fe2b.tar.xz | |
spi: stm32-qspi: Trigger DMA only if more than 4 bytes to transfer
In order to optimize accesses to spi flashes, trigger a DMA only
if more than 4 bytes has to be transferred.
DMA transfer preparation's cost becomes negligible above 4 bytes to
transfer. Below this threshold, indirect transfer give more throughput.
mtd_speedtest shows that page write throughtput increases :
- from 779 to 853 KiB/s (~9.5%) with s25fl512s SPI-NOR.
- from 5283 to 5666 KiB/s (~7.25%) with Micron SPI-NAND.
Signed-off-by: Christophe Kerello <christophe.kerello@foss.st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Link: https://lore.kernel.org/r/20210419121541.11617-3-patrice.chotard@foss.st.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/spi-stm32-qspi.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/spi/spi-stm32-qspi.c b/drivers/spi/spi-stm32-qspi.c index 2786470a5201..6e74d6bed54c 100644 --- a/drivers/spi/spi-stm32-qspi.c +++ b/drivers/spi/spi-stm32-qspi.c @@ -269,8 +269,9 @@ static int stm32_qspi_tx(struct stm32_qspi *qspi, const struct spi_mem_op *op) if (qspi->fmode == CCR_FMODE_MM) return stm32_qspi_tx_mm(qspi, op); - else if ((op->data.dir == SPI_MEM_DATA_IN && qspi->dma_chrx) || - (op->data.dir == SPI_MEM_DATA_OUT && qspi->dma_chtx)) + else if (((op->data.dir == SPI_MEM_DATA_IN && qspi->dma_chrx) || + (op->data.dir == SPI_MEM_DATA_OUT && qspi->dma_chtx)) && + op->data.nbytes > 4) if (!stm32_qspi_tx_dma(qspi, op)) return 0; |