dmaengine: at_xdmac: enhance channel errors handling in tasklet

Complement the identification of errors with stopping the channel and
dumping the descriptor that led to the error case.

Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 42 insertions, 6 deletions

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index 37a269420435..1dd7edaefbdc 100644
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -1575,6 +1575,46 @@ static void at_xdmac_handle_cyclic(struct at_xdmac_chan *atchan)
                 dmaengine_desc_get_callback_invoke(txd, NULL);
 }
 
+static void at_xdmac_handle_error(struct at_xdmac_chan *atchan)
+{
+        struct at_xdmac         *atxdmac = to_at_xdmac(atchan->chan.device);
+        struct at_xdmac_desc    *bad_desc;
+
+        /*
+         * The descriptor currently at the head of the active list is
+         * broken. Since we don't have any way to report errors, we'll
+         * just have to scream loudly and try to continue with other
+         * descriptors queued (if any).
+         */
+        if (atchan->irq_status & AT_XDMAC_CIS_RBEIS)
+                dev_err(chan2dev(&atchan->chan), "read bus error!!!");
+        if (atchan->irq_status & AT_XDMAC_CIS_WBEIS)
+                dev_err(chan2dev(&atchan->chan), "write bus error!!!");
+        if (atchan->irq_status & AT_XDMAC_CIS_ROIS)
+                dev_err(chan2dev(&atchan->chan), "request overflow error!!!");
+
+        spin_lock_bh(&atchan->lock);
+
+        /* Channel must be disabled first as it's not done automatically */
+        at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask);
+        while (at_xdmac_read(atxdmac, AT_XDMAC_GS) & atchan->mask)
+                cpu_relax();
+
+        bad_desc = list_first_entry(&atchan->xfers_list,
+                                    struct at_xdmac_desc,
+                                    xfer_node);
+
+        spin_unlock_bh(&atchan->lock);
+
+        /* Print bad descriptor's details if needed */
+        dev_dbg(chan2dev(&atchan->chan),
+                "%s: lld: mbr_sa=%pad, mbr_da=%pad, mbr_ubc=0x%08x\n",
+                __func__, &bad_desc->lld.mbr_sa, &bad_desc->lld.mbr_da,
+                bad_desc->lld.mbr_ubc);
+
+        /* Then continue with usual descriptor management */
+}
+
 static void at_xdmac_tasklet(unsigned long data)
 {
         struct at_xdmac_chan    *atchan = (struct at_xdmac_chan *)data;
@@ -1594,12 +1634,8 @@ static void at_xdmac_tasklet(unsigned long data)
                    || (atchan->irq_status & error_mask)) {
                 struct dma_async_tx_descriptor  *txd;
 
-                if (atchan->irq_status & AT_XDMAC_CIS_RBEIS)
-                        dev_err(chan2dev(&atchan->chan), "read bus error!!!");
-                if (atchan->irq_status & AT_XDMAC_CIS_WBEIS)
-                        dev_err(chan2dev(&atchan->chan), "write bus error!!!");
-                if (atchan->irq_status & AT_XDMAC_CIS_ROIS)
-                        dev_err(chan2dev(&atchan->chan), "request overflow error!!!");
+                if (atchan->irq_status & error_mask)
+                        at_xdmac_handle_error(atchan);
 
                 spin_lock(&atchan->lock);
                 desc = list_first_entry(&atchan->xfers_list,