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dmaengine: dw: don't perform DMA when dmaengine_submit is called

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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: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Andy Shevchenko 2014-06-18 12:15:38 +03:00 committed by Vinod Koul
parent cba15617c3
commit dd8ecfcac6
2 changed files with 7 additions and 13 deletions
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1
drivers/dma/TODO
View File

@ -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.

19
drivers/dma/dw/core.c
View File

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