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Commit dd8ecfca authored by Andy Shevchenko's avatar Andy Shevchenko Committed by Vinod Koul
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dmaengine: dw: don't perform DMA when dmaengine_submit is called 

Accordingly to discussion [1] and followed up documentation the DMA controller
driver shouldn't start any DMA operations when dmaengine_submit() is called.

This patch fixes the workflow in dw_dmac driver to follow the documentation.

[1] http://www.spinics.net/lists/arm-kernel/msg125987.html



Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: default avatarVinod Koul <vinod.koul@intel.com>
parent cba15617

drivers/dma/TODO

+0 −1
Original line number Diff line number Diff line
@@ -7,7 +7,6 @@ TODO for slave dma 
	- imx-dma

	- imx-sdma

	- mxs-dma.c

	- dw_dmac

	- intel_mid_dma

4. Check other subsystems for dma drivers and merge/move to dmaengine

5. Remove dma_slave_config's dma direction.

drivers/dma/dw/core.c

+7 −12
Original line number Diff line number Diff line
@@ -684,17 +684,9 @@ static dma_cookie_t dwc_tx_submit(struct dma_async_tx_descriptor *tx) 
	 * possible, perhaps even appending to those already submitted

	 * for DMA. But this is hard to do in a race-free manner.

	 */

	if (list_empty(&dwc->active_list)) {

		dev_vdbg(chan2dev(tx->chan), "%s: started %u\n", __func__,

				desc->txd.cookie);

		list_add_tail(&desc->desc_node, &dwc->active_list);

		dwc_dostart(dwc, dwc_first_active(dwc));

	} else {

		dev_vdbg(chan2dev(tx->chan), "%s: queued %u\n", __func__,

				desc->txd.cookie);



	dev_vdbg(chan2dev(tx->chan), "%s: queued %u\n", __func__, desc->txd.cookie);

	list_add_tail(&desc->desc_node, &dwc->queue);

	}



	spin_unlock_irqrestore(&dwc->lock, flags);
@@ -1099,9 +1091,12 @@ dwc_tx_status(struct dma_chan *chan, 
static void dwc_issue_pending(struct dma_chan *chan)

{

	struct dw_dma_chan	*dwc = to_dw_dma_chan(chan);

	unsigned long		flags;



	if (!list_empty(&dwc->queue))

		dwc_scan_descriptors(to_dw_dma(chan->device), dwc);

	spin_lock_irqsave(&dwc->lock, flags);

	if (list_empty(&dwc->active_list))

		dwc_dostart_first_queued(dwc);

	spin_unlock_irqrestore(&dwc->lock, flags);

}



static int dwc_alloc_chan_resources(struct dma_chan *chan)