[PATCH v6 04/15] DMA: PL330: Add DMA_CYCLIC capability

On Mon, Aug 22, 2011 at 5:33 PM, Boojin Kim [off-list ref] wrote:

quoted

quoted

+static struct dma_async_tx_descriptor *pl330_prep_dma_cyclic(
+ ? ? ? ? ? ? ? struct dma_chan *chan, dma_addr_t dma_addr, size_t len,
+ ? ? ? ? ? ? ? size_t period_len, enum dma_data_direction direction)
+{
+ ? ? ? struct dma_pl330_desc *desc;
+ ? ? ? struct dma_pl330_chan *pch = to_pchan(chan);
+ ? ? ? dma_addr_t dst;
+ ? ? ? dma_addr_t src;
+
+ ? ? ? desc = pl330_get_desc(pch);
+ ? ? ? if (!desc) {
+ ? ? ? ? ? ? ? dev_err(pch->dmac->pif.dev, "%s:%d Unable to fetch

desc\n",

quoted

+ ? ? ? ? ? ? ? ? ? ? ? __func__, __LINE__);
+ ? ? ? ? ? ? ? return NULL;
+ ? ? ? }
+
+ ? ? ? switch (direction) {
+ ? ? ? case DMA_TO_DEVICE:
+ ? ? ? ? ? ? ? desc->rqcfg.src_inc = 1;
+ ? ? ? ? ? ? ? desc->rqcfg.dst_inc = 0;
+ ? ? ? ? ? ? ? src = dma_addr;
+ ? ? ? ? ? ? ? dst = pch->fifo_addr;
+ ? ? ? ? ? ? ? break;
+ ? ? ? case DMA_FROM_DEVICE:
+ ? ? ? ? ? ? ? desc->rqcfg.src_inc = 0;
+ ? ? ? ? ? ? ? desc->rqcfg.dst_inc = 1;
+ ? ? ? ? ? ? ? src = pch->fifo_addr;
+ ? ? ? ? ? ? ? dst = dma_addr;
+ ? ? ? ? ? ? ? break;
+ ? ? ? default:
+ ? ? ? ? ? ? ? dev_err(pch->dmac->pif.dev, "%s:%d Invalid dma

direction\n",

quoted

+ ? ? ? ? ? ? ? __func__, __LINE__);
+ ? ? ? ? ? ? ? return NULL;
+ ? ? ? }
+
+ ? ? ? desc->rqcfg.brst_size = pch->burst_sz;
+ ? ? ? desc->rqcfg.brst_len = 1;
+
+ ? ? ? if (!pch->cyclic)
+ ? ? ? ? ? ? ? pch->cyclic = CYCLIC_PREP;

The need for check here seems suspicious.
Is it really needed? If not, please remove it.

It's required because Cyclic operation is passed from CYCLIC_PREP to
CYCLIC_TRIGGER.

I don't see why you need to differentiate between PREP and TRIGGER in
cyclic mode. I think, you should simply have 'bool cyclic' instead of enum.