On Wed, 2014-03-12 at 15:47 +0400, Alexander Popov wrote:

Introduce support for slave s/g transfer preparation and the associated
device control callback in the MPC512x DMA controller driver, which adds
support for data transfers between memory and peripheral I/O to the
previously supported mem-to-mem transfers.

2014?

[]

+static int mpc_dma_device_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
+							unsigned long arg)
+{
+	struct mpc_dma_chan *mchan;
+	struct mpc_dma *mdma;
+	struct dma_slave_config *cfg;
+	unsigned long flags;
+
+	mchan = dma_chan_to_mpc_dma_chan(chan);
+	switch (cmd) {
+	case DMA_TERMINATE_ALL:
+		/* Disable channel requests */
+		mdma = dma_chan_to_mpc_dma(chan);
+
+		spin_lock_irqsave(&mchan->lock, flags);
+
+		out_8(&mdma->regs->dmacerq, chan->chan_id);
+		list_splice_tail_init(&mchan->prepared, &mchan->free);
+		list_splice_tail_init(&mchan->queued, &mchan->free);
+		list_splice_tail_init(&mchan->active, &mchan->free);
+
+		spin_unlock_irqrestore(&mchan->lock, flags);
+
+		return 0;
+	case DMA_SLAVE_CONFIG:
+		/* Constraints:
+		 *  - only transfers between a peripheral device and
+		 *     memory are supported;
+		 *  - minimal transfer chunk is 4 bytes and consequently
+		 *     source and destination addresses must be 4-byte aligned
+		 *     and transfer size must be aligned on (4 * maxburst)
+		 *     boundary;
+		 *  - during the transfer RAM address is being incremented by
+		 *     the size of minimal transfer chunk;
+		 *  - peripheral port's address is constant during the transfer.
+		 */
+
+		cfg = (void *)arg;
+
+		if (!is_slave_direction(cfg->direction))
+			return -EINVAL;

As far as I understand the intention you have not to use direction field
in the dma_slave_config. It will be removed once.

+
+		if (cfg->src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES &&
+			cfg->dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
+			return -EINVAL;
+
+		spin_lock_irqsave(&mchan->lock, flags);
+
+		if (cfg->direction == DMA_DEV_TO_MEM) {
+			mchan->per_paddr = cfg->src_addr;
+			mchan->tcd_nunits = cfg->src_maxburst;
+		} else {
+			mchan->per_paddr = cfg->dst_addr;
+			mchan->tcd_nunits = cfg->dst_maxburst;
+		}

Ditto.


-- 
Andy Shevchenko [off-list ref]
Intel Finland Oy