On Wed, Jul 11, 2018 at 12:23:10AM +0800, Robin Gong wrote:

Add MEMCPY support, meanwhile, add SDMA_BD_MAX_CNT instead
of '0xffff'.

Signed-off-by: Robin Gong <redacted>
---
+static struct dma_async_tx_descriptor *sdma_prep_memcpy(
+		struct dma_chan *chan, dma_addr_t dma_dst,
+		dma_addr_t dma_src, size_t len, unsigned long flags)
+{
+	struct sdma_channel *sdmac = to_sdma_chan(chan);
+	struct sdma_engine *sdma = sdmac->sdma;
+	int channel = sdmac->channel;
+	size_t count;
+	int i = 0, param;
+	struct sdma_buffer_descriptor *bd;
+	struct sdma_desc *desc;
+
+	if (!chan || !len)
+		return NULL;
+
+	dev_dbg(sdma->dev, "memcpy: %pad->%pad, len=%zu, channel=%d.\n",
+		&dma_src, &dma_dst, len, channel);
+
+	desc = sdma_transfer_init(sdmac, DMA_MEM_TO_MEM, len / SDMA_BD_MAX_CNT
+					+ 1);
+	if (!desc)
+		goto err_out;
+
+	do {
+		count = min_t(size_t, len, SDMA_BD_MAX_CNT);

When len is bigger than 0xffff you initialize count to 0xffff...

+		bd = &desc->bd[i];
+		bd->buffer_addr = dma_src;
+		bd->ext_buffer_addr = dma_dst;
+		bd->mode.count = count;
+		desc->chn_count += count;
+
+		switch (sdmac->word_size) {
+		case DMA_SLAVE_BUSWIDTH_4_BYTES:
+			bd->mode.command = 0;
+			if ((count | dma_src | dma_dst) & 3)
+				goto err_bd_out;
+			break;

...In which case you bail out here with an error.

Please make sure bigger transfers are working.

+		case DMA_SLAVE_BUSWIDTH_2_BYTES:
+			bd->mode.command = 2;
+			if ((count | dma_src | dma_dst) & 1)
+				goto err_bd_out;
+			break;
+		case DMA_SLAVE_BUSWIDTH_1_BYTE:
+			bd->mode.command = 1;
+			break;
+		default:
+			goto err_bd_out;
+		}
+
+		dma_src += count;
+		dma_dst += count;
+		len -= count;
+		i++;
+
+		param = BD_DONE | BD_EXTD | BD_CONT;

Probably better readable if you drop BD_CONT here and do a

	if (len) {
		param |= BD_CONT;
	} else  {
		...
	}

Sascha

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