The DMAC expressed DMA request lengths as a number of transfers, limited
to 16777216 by the hardware. As a single transfer transfers a
configurable number of bytes (from 1 to 64), the chunk size limit isn't
fixed and must be computed at runtime by multiplying the transfers
number limit by the transfer size.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
---
drivers/dma/sh/rcar-dmac.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index 09df914..371cca3 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -242,7 +242,6 @@ struct rcar_dmac {
/* Hardcode the MEMCPY transfer size to 4 bytes. */
#define RCAR_DMAC_MEMCPY_XFER_SIZE 4
-#define RCAR_DMAC_MAX_XFER_LEN (RCAR_DMATCR_MASK + 1)
/* -----------------------------------------------------------------------------
* Device access
@@ -701,6 +700,7 @@ rcar_dmac_chan_prep_sg(struct rcar_dmac_chan *chan, struct scatterlist *sgl,
struct rcar_dmac_xfer_chunk *chunk;
struct rcar_dmac_desc *desc;
struct scatterlist *sg = sgl;
+ size_t max_chunk_size;
size_t full_size = 0;
unsigned int i;
@@ -716,6 +716,8 @@ rcar_dmac_chan_prep_sg(struct rcar_dmac_chan *chan, struct scatterlist *sgl,
rcar_dmac_chan_configure_desc(chan, desc);
+ max_chunk_size = (RCAR_DMATCR_MASK + 1) << desc->xfer_shift;
+
/*
* Allocate and fill the transfer chunk descriptors. We own the only
* reference to the DMA descriptor, there's no need for locking.
@@ -727,7 +729,7 @@ rcar_dmac_chan_prep_sg(struct rcar_dmac_chan *chan, struct scatterlist *sgl,
full_size += len;
while (len) {
- size_t size = min_t(size_t, len, RCAR_DMAC_MAX_XFER_LEN);
+ size_t size = min_t(size_t, len, max_chunk_size);
#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
/*
--
1.8.5.5
--
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