The sun6i DMA engine supports segment sizes up to 2^25-1 bytes. This is explicitly stated in newer SoC documentation (H6, D1), and it is implied in older documentation by the 25-bit width of the "bytes left in the current segment" register field. Exposing the real segment size limit (instead of the 64k default) reduces the number of SG list segments needed for a transaction. Reviewed-by: Jernej Skrabec <jernej.skrabec@xxxxxxxxx> Signed-off-by: Samuel Holland <samuel@xxxxxxxxxxxx> --- Tested on A64, verified that the maximum ALSA PCM period increased, and that audio playback still worked. Changes in v2: - Use SZ_32M instead of DMA_BIT_MASK to make the limit more obvious drivers/dma/sun6i-dma.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c index b7557f437936..30667d251e97 100644 --- a/drivers/dma/sun6i-dma.c +++ b/drivers/dma/sun6i-dma.c @@ -9,6 +9,7 @@ #include <linux/clk.h> #include <linux/delay.h> +#include <linux/dma-mapping.h> #include <linux/dmaengine.h> #include <linux/dmapool.h> #include <linux/interrupt.h> @@ -1334,6 +1335,8 @@ static int sun6i_dma_probe(struct platform_device *pdev) INIT_LIST_HEAD(&sdc->pending); spin_lock_init(&sdc->lock); + dma_set_max_seg_size(&pdev->dev, SZ_32M - 1); + dma_cap_set(DMA_PRIVATE, sdc->slave.cap_mask); dma_cap_set(DMA_MEMCPY, sdc->slave.cap_mask); dma_cap_set(DMA_SLAVE, sdc->slave.cap_mask); -- 2.37.4
