dmaengine: sa11x0-dma: fix DMA residue support

The semantics now implemented are:

- If the cookie has completed successfully, the residue will be zero.
- If the cookie is in progress or the channel is paused, it will be the
  number of bytes yet to be transferred. [*]
- If the cookie is queued, it will be the number of bytes in the
  descriptor.

* - where this is the number of bytes yet to be transferred to/from
  RAM.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 29 insertions, 16 deletions

diff --git a/drivers/dma/sa11x0-dma.c b/drivers/dma/sa11x0-dma.c
index 5f1d2e670837..db4fcbd80c7d 100644
--- a/drivers/dma/sa11x0-dma.c
+++ b/drivers/dma/sa11x0-dma.c
@@ -416,27 +416,47 @@ static enum dma_status sa11x0_dma_tx_status(struct dma_chan *chan,
         struct sa11x0_dma_chan *c = to_sa11x0_dma_chan(chan);
         struct sa11x0_dma_dev *d = to_sa11x0_dma(chan->device);
         struct sa11x0_dma_phy *p;
-        struct sa11x0_dma_desc *txd;
+        struct virt_dma_desc *vd;
         unsigned long flags;
         enum dma_status ret;
-        size_t bytes = 0;
 
         ret = dma_cookie_status(&c->vc.chan, cookie, state);
         if (ret == DMA_SUCCESS)
                 return ret;
 
+        if (!state)
+                return c->status;
+
         spin_lock_irqsave(&c->vc.lock, flags);
         p = c->phy;
-        ret = c->status;
-        if (p) {
-                dma_addr_t addr = sa11x0_dma_pos(p);
 
-                dev_vdbg(d->slave.dev, "tx_status: addr:%x\n", addr);
+        /*
+         * If the cookie is on our issue queue, then the residue is
+         * its total size.
+         */
+        vd = vchan_find_desc(&c->vc, cookie);
+        if (vd) {
+                state->residue = container_of(vd, struct sa11x0_dma_desc, vd)->size;
+        } else if (!p) {
+                state->residue = 0;
+        } else {
+                struct sa11x0_dma_desc *txd;
+                size_t bytes = 0;
+
+                if (p->txd_done && p->txd_done->vd.tx.cookie == cookie)
+                        txd = p->txd_done;
+                else if (p->txd_load && p->txd_load->vd.tx.cookie == cookie)
+                        txd = p->txd_load;
+                else
+                        txd = NULL;
 
-                txd = p->txd_done;
+                ret = c->status;
                 if (txd) {
+                        dma_addr_t addr = sa11x0_dma_pos(p);
                         unsigned i;
 
+                        dev_vdbg(d->slave.dev, "tx_status: addr:%x\n", addr);
+
                         for (i = 0; i < txd->sglen; i++) {
                                 dev_vdbg(d->slave.dev, "tx_status: [%u] %x+%x\n",
                                         i, txd->sg[i].addr, txd->sg[i].len);
@@ -459,18 +479,11 @@ static enum dma_status sa11x0_dma_tx_status(struct dma_chan *chan,
                                 bytes += txd->sg[i].len;
                         }
                 }
-                if (txd != p->txd_load && p->txd_load)
-                        bytes += p->txd_load->size;
-        }
-        list_for_each_entry(txd, &c->vc.desc_issued, vd.node) {
-                bytes += txd->size;
+                state->residue = bytes;
         }
         spin_unlock_irqrestore(&c->vc.lock, flags);
 
-        if (state)
-                state->residue = bytes;
-
-        dev_vdbg(d->slave.dev, "tx_status: bytes 0x%zx\n", bytes);
+        dev_vdbg(d->slave.dev, "tx_status: bytes 0x%zx\n", state->residue);
 
         return ret;
 }