Linux/AM5726: Problem transfer from DDR to PCI using EDMA

Part Number:AM5726

Tool/software: Linux

My linux kernel version:

Linux am57xx-evm 4.1.18-rt17 #1 SMP PREEMPT RT Thu Jun 29 11:43:34 DST 2017 armv7l GNU/Linux

My Problem:

time out when do dma from bf800000（DDR）to 24000000（pci 0000:01:00.0: BAR 0: assigned [mem 0x24000000-0x27ffffff]）length 256 Bytes

My Code:

static int tx_dma_transfer(struct dma_chan *chan, dma_addr_t dma_dst, dma_addr_t dma_src, size_t len)
{
	int rc = -ENODEV;
	dma_cookie_t cookie;
	struct completion cmp;
	enum dma_status status;
	enum dma_ctrl_flags flags = 0;
	struct dma_slave_config cfg;
	struct dma_async_tx_descriptor *tx = NULL;
	unsigned long tmo = msecs_to_jiffies(3000);
	
	if(!chan)
		goto done;
	
	memset(&cfg, 0, sizeof(cfg));
	cfg.direction = DMA_MEM_TO_DEV;
	cfg.src_addr = dma_src;
	cfg.dst_addr = dma_dst;
	cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
	cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
	cfg.src_maxburst = 16;
	cfg.dst_maxburst = 16;
	rc = dmaengine_slave_config(chan, &cfg);
	if (rc < 0)
		goto done;
	
	flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
	tx = dmaengine_prep_slave_single(chan, dma_src, len, DMA_MEM_TO_DEV, flags);
	if (!tx) {
	    printk(KERN_ERR "%s: Failed to prepare DMA transfer\n",
	           __FUNCTION__);
	    goto done;
	}
	
	init_completion(&cmp);
	tx->callback = dma_callback;
	tx->callback_param = &cmp;
	cookie = dmaengine_submit(tx);
	if (dma_submit_error(cookie)) {
	    printk(KERN_ERR "%s: Failed to start DMA transfer\n",
	           __FUNCTION__);
	           
	    rc = -ENOMEM;
	    goto done;
	}
	
	dma_async_issue_pending(chan);
	
	tmo = wait_for_completion_timeout(&cmp, tmo);
	status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
	
	if (tmo <= 0) {
		dmaengine_terminate_all(chan);
	    printk(KERN_ERR "%s: Transfer timed out\n", __FUNCTION__);
	    rc = -ETIMEDOUT;
	}
	if (status != DMA_COMPLETE) {
	    printk(KERN_ERR "%s: Transfer failed: status is %s\n",
	           __FUNCTION__,
	           status == DMA_ERROR ? "error" : "in progress");
	
	    dmaengine_terminate_all(chan);
	    rc = -EIO;
	}
	
done:
	return rc;
}

debug info after called:

[   59.429200] edma test from bf800000 to 24000000 len 256 

[   59.434377] edma 43300000.edma: first transfer starting on channel 4

[   59.440942] edma 43300000.edma: ER0 00000000

[   59.445232] edma 43300000.edma: EER0 00000010

[   62.448966] edma 43300000.edma: EER0 00000000

[   62.453343] tx_dma_transfer: Transfer timed out

[   62.457892] tx_dma_transfer: Transfer failed: status is in progress

 with EDMA