[PATCH v5 5/9] dmaengine: dw-edma: Fix programming the source & dest addresses for ep

[Frank Li <Frank.Li@nxp.com>]

From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

When eDMA is controlled by the Endpoint (EP), the current logic incorrectly
programs the source and destination addresses for read and write. Since the
Root complex and Endpoint uses the opposite channels for read/write, fix the
issue by finding out the read operation first and program the eDMA accordingly.

Cc: stable@vger.kernel.org
Fixes: bd96f1b2f43a ("dmaengine: dw-edma: support local dma device transfer semantics")
Fixes: e63d79d1ffcd ("dmaengine: Add Synopsys eDMA IP core driver")
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
 drivers/dma/dw-edma/dw-edma-core.c | 32 +++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
index 3e4850cfa0b72..924f220007362 100644
--- a/drivers/dma/dw-edma/dw-edma-core.c
+++ b/drivers/dma/dw-edma/dw-edma-core.c
@@ -334,6 +334,7 @@ dw_edma_device_transfer(struct dw_edma_transfer *xfer)
 	struct dw_edma_chunk *chunk;
 	struct dw_edma_burst *burst;
 	struct dw_edma_desc *desc;
+	bool read = false;
 	u32 cnt = 0;
 	int i;
 
@@ -424,7 +425,36 @@ dw_edma_device_transfer(struct dw_edma_transfer *xfer)
 		chunk->ll_region.sz += burst->sz;
 		desc->alloc_sz += burst->sz;
 
-		if (chan->dir == EDMA_DIR_WRITE) {
+		/****************************************************************
+		 *
+		 *        Root Complex                           Endpoint
+		 * +-----------------------+             +----------------------+
+		 * |                       |    TX CH    |                      |
+		 * |                       |             |                      |
+		 * |      DEV_TO_MEM       <-------------+     MEM_TO_DEV       |
+		 * |                       |             |                      |
+		 * |                       |             |                      |
+		 * |      MEM_TO_DEV       +------------->     DEV_TO_MEM       |
+		 * |                       |             |                      |
+		 * |                       |    RX CH    |                      |
+		 * +-----------------------+             +----------------------+
+		 *
+		 * If eDMA is controlled by the Root complex, TX channel
+		 * (EDMA_DIR_WRITE) is used for memory read (DEV_TO_MEM) and RX
+		 * channel (EDMA_DIR_READ) is used for memory write (MEM_TO_DEV).
+		 *
+		 * If eDMA is controlled by the endpoint, RX channel
+		 * (EDMA_DIR_READ) is used for memory read (DEV_TO_MEM) and TX
+		 * channel (EDMA_DIR_WRITE) is used for memory write (MEM_TO_DEV).
+		 *
+		 ****************************************************************/
+
+		if ((dir == DMA_DEV_TO_MEM && chan->dir == EDMA_DIR_READ) ||
+		    (dir == DMA_DEV_TO_MEM && chan->dir == EDMA_DIR_WRITE))
+			read = true;
+
+		/* Program the source and destination addresses for DMA read/write */
+		if (read) {
 			burst->sar = src_addr;
 			if (xfer->type == EDMA_XFER_CYCLIC) {
 				burst->dar = xfer->xfer.cyclic.paddr;
-- 
2.24.0.rc1