dmaengine: Move all map_sg/unmap_sg for slave channel to its client

Dan Williams wrote:
... DMA-slave clients request specific channels and know the hardware
details at a low level, so it should not be too high an expectation to
push dma mapping responsibility to the client.

Also this patch includes DMA_COMPL_{SRC,DEST}_UNMAP_SINGLE support for
dw_dmac driver.

Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/dma/at_hdmac.c

@@ -253,25 +253,28 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc)
 	list_move(&desc->desc_node, &atchan->free_list);
 
 	/* unmap dma addresses */
-	if (!(txd->flags & DMA_COMPL_SKIP_DEST_UNMAP)) {
-		if (txd->flags & DMA_COMPL_DEST_UNMAP_SINGLE)
-			dma_unmap_single(chan2parent(&atchan->chan_common),
-					desc->lli.daddr,
-					desc->len, DMA_FROM_DEVICE);
-		else
-			dma_unmap_page(chan2parent(&atchan->chan_common),
-					desc->lli.daddr,
-					desc->len, DMA_FROM_DEVICE);
-	}
-	if (!(txd->flags & DMA_COMPL_SKIP_SRC_UNMAP)) {
-		if (txd->flags & DMA_COMPL_SRC_UNMAP_SINGLE)
-			dma_unmap_single(chan2parent(&atchan->chan_common),
-					desc->lli.saddr,
-					desc->len, DMA_TO_DEVICE);
-		else
-			dma_unmap_page(chan2parent(&atchan->chan_common),
-					desc->lli.saddr,
-					desc->len, DMA_TO_DEVICE);
+	if (!atchan->chan_common.private) {
+		struct device *parent = chan2parent(&atchan->chan_common);
+		if (!(txd->flags & DMA_COMPL_SKIP_DEST_UNMAP)) {
+			if (txd->flags & DMA_COMPL_DEST_UNMAP_SINGLE)
+				dma_unmap_single(parent,
+						desc->lli.daddr,
+						desc->len, DMA_FROM_DEVICE);
+			else
+				dma_unmap_page(parent,
+						desc->lli.daddr,
+						desc->len, DMA_FROM_DEVICE);
+		}
+		if (!(txd->flags & DMA_COMPL_SKIP_SRC_UNMAP)) {
+			if (txd->flags & DMA_COMPL_SRC_UNMAP_SINGLE)
+				dma_unmap_single(parent,
+						desc->lli.saddr,
+						desc->len, DMA_TO_DEVICE);
+			else
+				dma_unmap_page(parent,
+						desc->lli.saddr,
+						desc->len, DMA_TO_DEVICE);
+		}
 	}
 
 	/*
@@ -647,8 +650,6 @@ atc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 
 	reg_width = atslave->reg_width;
 
-	sg_len = dma_map_sg(chan2parent(chan), sgl, sg_len, direction);
-
 	ctrla = ATC_DEFAULT_CTRLA | atslave->ctrla;
 	ctrlb = ATC_DEFAULT_CTRLB | ATC_IEN;
 

drivers/dma/dw_dmac.c

@@ -212,16 +212,25 @@ dwc_descriptor_complete(struct dw_dma_chan *dwc, struct dw_desc *desc)
 	list_splice_init(&desc->tx_list, &dwc->free_list);
 	list_move(&desc->desc_node, &dwc->free_list);
 
-	/*
-	 * We use dma_unmap_page() regardless of how the buffers were
-	 * mapped before they were submitted...
-	 */
-	if (!(txd->flags & DMA_COMPL_SKIP_DEST_UNMAP))
-		dma_unmap_page(chan2parent(&dwc->chan), desc->lli.dar,
-			       desc->len, DMA_FROM_DEVICE);
-	if (!(txd->flags & DMA_COMPL_SKIP_SRC_UNMAP))
-		dma_unmap_page(chan2parent(&dwc->chan), desc->lli.sar,
-			       desc->len, DMA_TO_DEVICE);
+	if (!dwc->chan.private) {
+		struct device *parent = chan2parent(&dwc->chan);
+		if (!(txd->flags & DMA_COMPL_SKIP_DEST_UNMAP)) {
+			if (txd->flags & DMA_COMPL_DEST_UNMAP_SINGLE)
+				dma_unmap_single(parent, desc->lli.dar,
+						desc->len, DMA_FROM_DEVICE);
+			else
+				dma_unmap_page(parent, desc->lli.dar,
+						desc->len, DMA_FROM_DEVICE);
+		}
+		if (!(txd->flags & DMA_COMPL_SKIP_SRC_UNMAP)) {
+			if (txd->flags & DMA_COMPL_SRC_UNMAP_SINGLE)
+				dma_unmap_single(parent, desc->lli.sar,
+						desc->len, DMA_TO_DEVICE);
+			else
+				dma_unmap_page(parent, desc->lli.sar,
+						desc->len, DMA_TO_DEVICE);
+		}
+	}
 
 	/*
 	 * The API requires that no submissions are done from a
@@ -658,8 +667,6 @@ dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 	reg_width = dws->reg_width;
 	prev = first = NULL;
 
-	sg_len = dma_map_sg(chan2parent(chan), sgl, sg_len, direction);
-
 	switch (direction) {
 	case DMA_TO_DEVICE:
 		ctllo = (DWC_DEFAULT_CTLLO

drivers/mmc/host/atmel-mci.c

@@ -576,6 +576,7 @@ atmci_submit_data_dma(struct atmel_mci *host, struct mmc_data *data)
 	struct scatterlist		*sg;
 	unsigned int			i;
 	enum dma_data_direction		direction;
+	unsigned int			sglen;
 
 	/*
 	 * We don't do DMA on "complex" transfers, i.e. with
@@ -605,11 +606,14 @@ atmci_submit_data_dma(struct atmel_mci *host, struct mmc_data *data)
 	else
 		direction = DMA_TO_DEVICE;
 
+	sglen = dma_map_sg(&host->pdev->dev, data->sg, data->sg_len, direction);
+	if (sglen != data->sg_len)
+		goto unmap_exit;
 	desc = chan->device->device_prep_slave_sg(chan,
 			data->sg, data->sg_len, direction,
 			DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 	if (!desc)
-		return -ENOMEM;
+		goto unmap_exit;
 
 	host->dma.data_desc = desc;
 	desc->callback = atmci_dma_complete;
@@ -620,6 +624,9 @@ atmci_submit_data_dma(struct atmel_mci *host, struct mmc_data *data)
 	chan->device->device_issue_pending(chan);
 
 	return 0;
+unmap_exit:
+	dma_unmap_sg(&host->pdev->dev, data->sg, sglen, direction);
+	return -ENOMEM;
 }
 
 #else /* CONFIG_MMC_ATMELMCI_DMA */