[PATCH v6 1/3] dma: at_xdmac: creation of the atmel eXtended DMA Controller driver

Hi Vinod,

On Wed, Oct 15, 2014 at 07:00:04PM +0530, Vinod Koul wrote:

On Wed, Oct 01, 2014 at 04:59:23PM +0200, Ludovic Desroches wrote:

quoted

New atmel DMA controller known as XDMAC, introduced with SAMA5D4
devices.

+static int at_xdmac_set_slave_config(struct dma_chan *chan,
+				      struct dma_slave_config *sconfig)
+{
+	struct at_xdmac_chan 	*atchan = to_at_xdmac_chan(chan);
+
+	atchan->cfg = AT91_XDMAC_DT_PERID(atchan->perid)
+		      |	AT_XDMAC_CC_SWREQ_HWR_CONNECTED
+		      | AT_XDMAC_CC_MBSIZE_SIXTEEN
+		      | AT_XDMAC_CC_TYPE_PER_TRAN;
+
+	if (sconfig->direction == DMA_DEV_TO_MEM) {
+		atchan->cfg |= AT_XDMAC_CC_DAM_INCREMENTED_AM
+			       | AT_XDMAC_CC_SAM_FIXED_AM
+			       | AT_XDMAC_CC_DIF(atchan->memif)
+			       | AT_XDMAC_CC_SIF(atchan->perif)
+			       | AT_XDMAC_CC_DSYNC_PER2MEM;
+		atchan->dwidth = ffs(sconfig->src_addr_width) - 1;
+		atchan->cfg |= AT_XDMAC_CC_DWIDTH(atchan->dwidth);
+		atchan->cfg |= at_xdmac_csize(sconfig->src_maxburst);
+	} else if (sconfig->direction == DMA_MEM_TO_DEV) {
+		atchan->cfg |= AT_XDMAC_CC_DAM_FIXED_AM
+			       | AT_XDMAC_CC_SAM_INCREMENTED_AM
+			       | AT_XDMAC_CC_DIF(atchan->perif)
+			       | AT_XDMAC_CC_SIF(atchan->memif)
+			       | AT_XDMAC_CC_DSYNC_MEM2PER;
+		atchan->dwidth = ffs(sconfig->dst_addr_width) - 1;
+		atchan->cfg |= AT_XDMAC_CC_DWIDTH(atchan->dwidth);
+		atchan->cfg |= at_xdmac_csize(sconfig->dst_maxburst);

please store both direction configs and use them based on direction in
prep_xxx calls. We will remove the direction here.

Ok so direction will disappear the dma_slave_config structure I assume
but what is planned for src/dst_addr_width and src/dst_maxburst. If
slave config looses the direction, there is no sense to have some src
and dst fields. So where should I get them?

quoted

+	} else {
+		return -EINVAL;
+	}
+
+	/*
+	 * Src address and dest addr are needed to configure the link list
+	 * descriptor so keep the slave configuration.
+	 */
+	memcpy(&atchan->dma_sconfig, sconfig, sizeof(struct dma_slave_config));
+
+	dev_dbg(chan2dev(chan), "%s: atchan->cfg=0x%08x\n", __func__, atchan->cfg);
+
+	return 0;
+}

Ludovic