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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: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Robert Jarzmik 2016-03-28 23:32:24 +02:00 committed by Vinod Koul
parent f55532a0c0
commit e093bf60ca
1 changed files with 13 additions and 1 deletions
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14
drivers/dma/pxa_dma.c
View File

@ -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));