dmaengine: pl330: fix residual for non-running BUSY descriptors

Only one descriptor in the work list should be running at
any given time, but it's possible to have an enqueued BUSY
descriptor that has not yet transferred any data, or for
a BUSY descriptor to linger briefly before transitioning
to DONE. These cases should be handled to keep residual
calculations consistent even with the non-running BUSY
descriptors in the work list.

Signed-off-by: Stephen Barber <smbarber@chromium.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index 4fc3ffbd5ca0d0a36b489eceba61091b323228e3..31e9c49e56049842a291f092ba9228cafa32aa8b 100644 (file)
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -2274,7 +2274,7 @@ pl330_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
 {
        enum dma_status ret;
        unsigned long flags;
-       struct dma_pl330_desc *desc, *running = NULL;
+       struct dma_pl330_desc *desc, *running = NULL, *last_enq = NULL;
        struct dma_pl330_chan *pch = to_pchan(chan);
        unsigned int transferred, residual = 0;
 
@@ -2291,6 +2291,8 @@ pl330_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
        if (pch->thread->req_running != -1)
                running = pch->thread->req[pch->thread->req_running].desc;
 
+       last_enq = pch->thread->req[pch->thread->lstenq].desc;
+
        /* Check in pending list */
        list_for_each_entry(desc, &pch->work_list, node) {
                if (desc->status == DONE)
@@ -2298,6 +2300,15 @@ pl330_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
                else if (running && desc == running)
                        transferred =
                                pl330_get_current_xferred_count(pch, desc);
+               else if (desc->status == BUSY)
+                       /*
+                        * Busy but not running means either just enqueued,
+                        * or finished and not yet marked done
+                        */
+                       if (desc == last_enq)
+                               transferred = 0;
+                       else
+                               transferred = desc->bytes_requested;
                else
                        transferred = 0;
                residual += desc->bytes_requested - transferred;