On Mon, Sep 23, 2013 at 06:05:14PM -0500, Joel Fernandes wrote:
> @@ -449,6 +455,138 @@ static struct dma_async_tx_descriptor *edma_prep_slave_sg(
> return vchan_tx_prep(&echan->vchan, &edesc->vdesc, tx_flags);
> }
>
> +static struct dma_async_tx_descriptor *edma_prep_dma_cyclic(
> + struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
> + size_t period_len, enum dma_transfer_direction direction,
> + unsigned long tx_flags, void *context)
> +{
> + struct edma_chan *echan = to_edma_chan(chan);
> + struct device *dev = chan->device->dev;
> + struct edma_desc *edesc;
> + dma_addr_t src_addr, dst_addr;
> + enum dma_slave_buswidth dev_width;
> + u32 burst;
> + int i, ret, nr_periods;
> +
> + if (unlikely(!echan || !buf_len || !period_len))
> + return NULL;
> +
> + if (direction == DMA_DEV_TO_MEM) {
> + src_addr = echan->cfg.src_addr;
> + dst_addr = buf_addr;
> + dev_width = echan->cfg.src_addr_width;
> + burst = echan->cfg.src_maxburst;
> + } else if (direction == DMA_MEM_TO_DEV) {
> + src_addr = buf_addr;
> + dst_addr = echan->cfg.dst_addr;
> + dev_width = echan->cfg.dst_addr_width;
> + burst = echan->cfg.dst_maxburst;
> + } else {
> + dev_err(dev, "%s: bad direction?\n", __func__);
> + return NULL;
> + }
> +
> + if (dev_width == DMA_SLAVE_BUSWIDTH_UNDEFINED) {
> + dev_err(dev, "Undefined slave buswidth\n");
> + return NULL;
> + }
> +
> + if (unlikely(buf_len % period_len)) {
> + dev_err(dev, "Period should be multiple of Buffer length\n");
> + return NULL;
> + }
> +
> + nr_periods = (buf_len / period_len) + 1;
?
consider the case of buf = period_len, above makes nr_period = 2.
Or buf len 100, period len 50, makes nr_period = 3
Both doesnt seem right to me?
--
~Vinod
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