dmaengine: edma: Sanitize residue reporting

The residue reporting in edma_tx_status() is just broken. It blindly
walks the psets and recalculates the lenght of the transfer from the
hardware parameters. For cyclic transfers it adds the link pset, which
results in interestingly large residues. For non-cyclic it adds the
dummy pset, which is stupid as well.

Aside of that it's silly to walk through the pset params when the per
descriptor residue is known at the point of creating it.

Store the information in edma_desc and use it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Joel Fernandes <joelf@ti.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/edma.c

@@ -64,6 +64,7 @@ struct edma_desc {
 	int				absync;
 	int				pset_nr;
 	int				processed;
+	u32				residue;
 	struct edmacc_param		pset[0];
 };
 
@@ -456,6 +457,7 @@ static struct dma_async_tx_descriptor *edma_prep_slave_sg(
 	}
 
 	edesc->pset_nr = sg_len;
+	edesc->residue = 0;
 
 	/* Allocate a PaRAM slot, if needed */
 	nslots = min_t(unsigned, MAX_NR_SG, sg_len);
@@ -491,6 +493,7 @@ static struct dma_async_tx_descriptor *edma_prep_slave_sg(
 		}
 
 		edesc->absync = ret;
+		edesc->residue += sg_dma_len(sg);
 
 		/* If this is the last in a current SG set of transactions,
 		   enable interrupts so that next set is processed */
@@ -606,6 +609,7 @@ static struct dma_async_tx_descriptor *edma_prep_dma_cyclic(
 
 	edesc->cyclic = 1;
 	edesc->pset_nr = nslots;
+	edesc->residue = buf_len;
 
 	dev_dbg(dev, "%s: channel=%d nslots=%d period_len=%zu buf_len=%zu\n",
 		__func__, echan->ch_num, nslots, period_len, buf_len);
@@ -700,6 +704,7 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
 				vchan_cyclic_callback(&edesc->vdesc);
 			} else if (edesc->processed == edesc->pset_nr) {
 				dev_dbg(dev, "Transfer complete, stopping channel %d\n", ch_num);
+				edesc->residue = 0;
 				edma_stop(echan->ch_num);
 				vchan_cookie_complete(&edesc->vdesc);
 				edma_execute(echan);
@@ -832,25 +837,6 @@ static void edma_issue_pending(struct dma_chan *chan)
 	spin_unlock_irqrestore(&echan->vchan.lock, flags);
 }
 
-static size_t edma_desc_size(struct edma_desc *edesc)
-{
-	int i;
-	size_t size;
-
-	if (edesc->absync)
-		for (size = i = 0; i < edesc->pset_nr; i++)
-			size += (edesc->pset[i].a_b_cnt & 0xffff) *
-				(edesc->pset[i].a_b_cnt >> 16) *
-				 edesc->pset[i].ccnt;
-	else
-		size = (edesc->pset[0].a_b_cnt & 0xffff) *
-			(edesc->pset[0].a_b_cnt >> 16) +
-			(edesc->pset[0].a_b_cnt & 0xffff) *
-			(SZ_64K - 1) * edesc->pset[0].ccnt;
-
-	return size;
-}
-
 /* Check request completion status */
 static enum dma_status edma_tx_status(struct dma_chan *chan,
 				      dma_cookie_t cookie,
@@ -867,12 +853,10 @@ static enum dma_status edma_tx_status(struct dma_chan *chan,
 
 	spin_lock_irqsave(&echan->vchan.lock, flags);
 	vdesc = vchan_find_desc(&echan->vchan, cookie);
-	if (vdesc) {
-		txstate->residue = edma_desc_size(to_edma_desc(&vdesc->tx));
-	} else if (echan->edesc && echan->edesc->vdesc.tx.cookie == cookie) {
-		struct edma_desc *edesc = echan->edesc;
-		txstate->residue = edma_desc_size(edesc);
-	}
+	if (vdesc)
+		txstate->residue = to_edma_desc(&vdesc->tx)->residue;
+	else if (echan->edesc && echan->edesc->vdesc.tx.cookie == cookie)
+		txstate->residue = echan->edesc->residue;
 	spin_unlock_irqrestore(&echan->vchan.lock, flags);
 
 	return ret;