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Commit 8a489b0b authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by Greg Kroah-Hartman
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dmaengine: pl330: Return DMA_PAUSED when transaction is paused 



commit 8cda3ececf07d374774f6a13e5a94bc2dc04c26c upstream.

pl330_pause() does not set anything to indicate paused condition which
causes pl330_tx_status() to return DMA_IN_PROGRESS. This breaks 8250
DMA flush after the fix in commit 57e9af7831dc ("serial: 8250_dma: Fix
DMA Rx rearm race"). The function comment for pl330_pause() claims
pause is supported but resume is not which is enough for 8250 DMA flush
to work as long as DMA status reports DMA_PAUSED when appropriate.

Add PAUSED state for descriptor and mark BUSY descriptors with PAUSED
in pl330_pause(). Return DMA_PAUSED from pl330_tx_status() when the
descriptor is PAUSED.

Reported-by: default avatarRichard Tresidder <rtresidd@electromag.com.au>
Tested-by: default avatarRichard Tresidder <rtresidd@electromag.com.au>
Fixes: 88987d2c ("dmaengine: pl330: add DMA_PAUSE feature")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/linux-serial/f8a86ecd-64b1-573f-c2fa-59f541083f1a@electromag.com.au/


Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230526105434.14959-1-ilpo.jarvinen@linux.intel.com


Signed-off-by: default avatarVinod Koul <vkoul@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7c62508d

drivers/dma/pl330.c

+16 −2
Original line number Diff line number Diff line
@@ -402,6 +402,12 @@ enum desc_status { 
	 * of a channel can be BUSY at any time.

	 */

	BUSY,

	/*

	 * Pause was called while descriptor was BUSY. Due to hardware

	 * limitations, only termination is possible for descriptors

	 * that have been paused.

	 */

	PAUSED,

	/*

	 * Sitting on the channel work_list but xfer done

	 * by PL330 core
@@ -2035,7 +2041,7 @@ static inline void fill_queue(struct dma_pl330_chan *pch) 
	list_for_each_entry(desc, &pch->work_list, node) {



		/* If already submitted */

		if (desc->status == BUSY)

		if (desc->status == BUSY || desc->status == PAUSED)

			continue;



		ret = pl330_submit_req(pch->thread, desc);
@@ -2322,6 +2328,7 @@ static int pl330_pause(struct dma_chan *chan) 
{

	struct dma_pl330_chan *pch = to_pchan(chan);

	struct pl330_dmac *pl330 = pch->dmac;

	struct dma_pl330_desc *desc;

	unsigned long flags;



	pm_runtime_get_sync(pl330->ddma.dev);
@@ -2331,6 +2338,10 @@ static int pl330_pause(struct dma_chan *chan) 
	_stop(pch->thread);

	spin_unlock(&pl330->lock);



	list_for_each_entry(desc, &pch->work_list, node) {

		if (desc->status == BUSY)

			desc->status = PAUSED;

	}

	spin_unlock_irqrestore(&pch->lock, flags);

	pm_runtime_mark_last_busy(pl330->ddma.dev);

	pm_runtime_put_autosuspend(pl330->ddma.dev);
@@ -2421,7 +2432,7 @@ pl330_tx_status(struct dma_chan *chan, dma_cookie_t cookie, 
		else if (running && desc == running)

			transferred =

				pl330_get_current_xferred_count(pch, desc);

		else if (desc->status == BUSY)

		else if (desc->status == BUSY || desc->status == PAUSED)

			/*

			 * Busy but not running means either just enqueued,

			 * or finished and not yet marked done
@@ -2438,6 +2449,9 @@ pl330_tx_status(struct dma_chan *chan, dma_cookie_t cookie, 
			case DONE:

				ret = DMA_COMPLETE;

				break;

			case PAUSED:

				ret = DMA_PAUSED;

				break;

			case PREP:

			case BUSY:

				ret = DMA_IN_PROGRESS;