[PATCH] spi: bcm2835: only split transfers that exceed DLEN if DMA available

From: Nicolas Saenz Julienne
Date: Thu May 09 2019 - 10:41:16 EST


There is no use for this when performing non DMA operations. So we
bypass the split.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx>
---
drivers/spi/spi-bcm2835.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 37893313e595..649fd6caed35 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -861,15 +861,17 @@ static int bcm2835_spi_prepare_message(struct spi_master *master,
u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
int ret;

- /*
- * DMA transfers are limited to 16 bit (0 to 65535 bytes) by the SPI HW
- * due to DLEN. Split up transfers (32-bit FIFO aligned) if the limit is
- * exceeded.
- */
- ret = spi_split_transfers_maxsize(master, msg, 65532,
- GFP_KERNEL | GFP_DMA);
- if (ret)
- return ret;
+ if (master->can_dma) {
+ /*
+ * DMA transfers are limited to 16 bit (0 to 65535 bytes) by
+ * the SPI HW due to DLEN. Split up transfers (32-bit FIFO
+ * aligned) if the limit is exceeded.
+ */
+ ret = spi_split_transfers_maxsize(master, msg, 65532,
+ GFP_KERNEL | GFP_DMA);
+ if (ret)
+ return ret;
+ }

cs &= ~(BCM2835_SPI_CS_CPOL | BCM2835_SPI_CS_CPHA);

--
2.21.0