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Commit e093bf60 authored by Robert Jarzmik's avatar Robert Jarzmik Committed by Vinod Koul
Browse files

dmaengine: pxa: handle bus errors 



In the current state, upon bus error the driver will spin endlessly,
relaunching the last tx, which will fail again and again :
 - a bus error happens
 - pxad_chan_handler() is called
 - as PXA_DCSR_STOPSTATE is true, the last non-terminated transaction is
   lauched, which is the one triggering the bus error, as it didn't
   terminate
 - moreover, the STOP interrupt fires a new, as the STOPIRQEN is still
   active

Break this logic by stopping the automatic relaunch of a dma channel
upon a bus error, even if there are still pending issued requests on it.

As dma_cookie_status() seems unable to return DMA_ERROR in its current
form, ie. there seems no way to mark a DMA_ERROR on a per-async-tx
basis, it is chosen in this patch to remember on the channel which
transaction failed, and report it in pxad_tx_status().

It's a bit misleading because if T1, T2, T3 and T4 were queued, and T1
was completed while T2 causes a bus error, the status of T3 and T4 will
be reported as DMA_IN_PROGRESS, while the channel is actually stopped.

Signed-off-by: default avatarRobert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: default avatarVinod Koul <vinod.koul@intel.com>
parent f55532a0

drivers/dma/pxa_dma.c

+13 −1
Original line number Diff line number Diff line
@@ -117,6 +117,7 @@ struct pxad_chan { 
	/* protected by vc->lock */

	struct pxad_phy		*phy;

	struct dma_pool		*desc_pool;	/* Descriptors pool */

	dma_cookie_t		bus_error;

};



struct pxad_device {
@@ -563,6 +564,7 @@ static void pxad_launch_chan(struct pxad_chan *chan, 
			return;

		}

	}

	chan->bus_error = 0;



	/*

	 * Program the descriptor's address into the DMA controller,
@@ -666,6 +668,7 @@ static irqreturn_t pxad_chan_handler(int irq, void *dev_id) 
	struct virt_dma_desc *vd, *tmp;

	unsigned int dcsr;

	unsigned long flags;

	dma_cookie_t last_started = 0;



	BUG_ON(!chan);
@@ -678,6 +681,7 @@ static irqreturn_t pxad_chan_handler(int irq, void *dev_id) 
		dev_dbg(&chan->vc.chan.dev->device,

			"%s(): checking txd %p[%x]: completed=%d\n",

			__func__, vd, vd->tx.cookie, is_desc_completed(vd));

		last_started = vd->tx.cookie;

		if (to_pxad_sw_desc(vd)->cyclic) {

			vchan_cyclic_callback(vd);

			break;
@@ -690,7 +694,12 @@ static irqreturn_t pxad_chan_handler(int irq, void *dev_id) 
		}

	}



	if (dcsr & PXA_DCSR_STOPSTATE) {

	if (dcsr & PXA_DCSR_BUSERR) {

		chan->bus_error = last_started;

		phy_disable(phy);

	}



	if (!chan->bus_error && dcsr & PXA_DCSR_STOPSTATE) {

		dev_dbg(&chan->vc.chan.dev->device,

		"%s(): channel stopped, submitted_empty=%d issued_empty=%d",

			__func__,
@@ -1249,6 +1258,9 @@ static enum dma_status pxad_tx_status(struct dma_chan *dchan, 
	struct pxad_chan *chan = to_pxad_chan(dchan);

	enum dma_status ret;



	if (cookie == chan->bus_error)

		return DMA_ERROR;



	ret = dma_cookie_status(dchan, cookie, txstate);

	if (likely(txstate && (ret != DMA_ERROR)))

		dma_set_residue(txstate, pxad_residue(chan, cookie));