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 77c1c44009d87115f2c44d5fd698dc8a1626ec51..6d17dfd67881a7fe314b917bc6dc7e4b65e91946 100644 (file)
--- a/drivers/dma/pxa_dma.c
+++ b/drivers/dma/pxa_dma.c
@@ -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));