diff options
Diffstat (limited to 'recipes-kernel/linux/linux-3.12.70/linux-3.12-spi-atmel-dma-min.patch')
| -rw-r--r-- | recipes-kernel/linux/linux-3.12.70/linux-3.12-spi-atmel-dma-min.patch | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/recipes-kernel/linux/linux-3.12.70/linux-3.12-spi-atmel-dma-min.patch b/recipes-kernel/linux/linux-3.12.70/linux-3.12-spi-atmel-dma-min.patch new file mode 100644 index 0000000..4aba504 --- /dev/null +++ b/recipes-kernel/linux/linux-3.12.70/linux-3.12-spi-atmel-dma-min.patch @@ -0,0 +1,18 @@ +Index: linux-3.12.27/drivers/spi/spi-atmel.c +=================================================================== +--- linux-3.12.27.orig/drivers/spi/spi-atmel.c ++++ linux-3.12.27/drivers/spi/spi-atmel.c +@@ -187,7 +187,12 @@ + /* use PIO for small transfers, avoiding DMA setup/teardown overhead and + * cache operations; better heuristics consider wordsize and bitrate. + */ +-#define DMA_MIN_BYTES 16 ++ ++/* MTS: set DMA_MIN_BYTES=0 to use DMA all the time due to Rx buffer issues ++ * when switching between smaller PIO and larger DMA transfers ++ * https://lkml.org/lkml/2013/10/21/534 ++ */ ++#define DMA_MIN_BYTES 0 + + struct atmel_spi_dma { + struct dma_chan *chan_rx; |