[PATCH v1 1/4] dmaengine: imx-sdma: add memcpy interface

Sascha Hauer
2018-07-11T06:24:34Z

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 <yibin.gong@nxp.com>
> ---
> +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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