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>
diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c
index 77c1c44..6d17dfd 100644
--- a/drivers/dma/pxa_dma.c
+++ b/drivers/dma/pxa_dma.c
@@ -117,6 +117,7 @@
/* 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 @@
return;
}
}
+ chan->bus_error = 0;
/*
* Program the descriptor's address into the DMA controller,
@@ -666,6 +668,7 @@
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 @@
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 @@
}
}
- 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 @@
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));