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authorPatrice Chotard <patrice.chotard@foss.st.com>2021-04-19 15:15:40 +0300
committerMark Brown <broonie@kernel.org>2021-04-19 16:18:43 +0300
commitf3530f26f8e9869e6e8c3370cf6f61330774fe2b (patch)
tree6649974505754d1e73b965cd5e0dc18dd73dc599 /drivers/spi
parent102e9d1936569d43f55dd1ea89be355ad207143c (diff)
downloadlinux-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.c5
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;