dmaengine: rcar-dmac: Fix residue reporting for pending descriptors

Cookies corresponding to pending transfers have a residue value equal to
the full size of the corresponding descriptor. The driver miscomputes
that and uses the size of the active descriptor instead. Fix it.

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
[geert: Also check desc.active list]
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index 561476c1e741866c332fa95f04229af097c1e9a4..0dd953884d1d63eb90e3b1599aedcb3f02ac0caa 100644 (file)
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -1145,19 +1145,46 @@ static unsigned int rcar_dmac_chan_get_residue(struct rcar_dmac_chan *chan,
        struct rcar_dmac_desc *desc = chan->desc.running;
        struct rcar_dmac_xfer_chunk *running = NULL;
        struct rcar_dmac_xfer_chunk *chunk;
+       enum dma_status status;
        unsigned int residue = 0;
        unsigned int dptr = 0;
 
        if (!desc)
                return 0;
 
+       /*
+        * If the cookie corresponds to a descriptor that has been completed
+        * there is no residue. The same check has already been performed by the
+        * caller but without holding the channel lock, so the descriptor could
+        * now be complete.
+        */
+       status = dma_cookie_status(&chan->chan, cookie, NULL);
+       if (status == DMA_COMPLETE)
+               return 0;
+
        /*
         * If the cookie doesn't correspond to the currently running transfer
         * then the descriptor hasn't been processed yet, and the residue is
         * equal to the full descriptor size.
         */
-       if (cookie != desc->async_tx.cookie)
-               return desc->size;
+       if (cookie != desc->async_tx.cookie) {
+               list_for_each_entry(desc, &chan->desc.pending, node) {
+                       if (cookie == desc->async_tx.cookie)
+                               return desc->size;
+               }
+               list_for_each_entry(desc, &chan->desc.active, node) {
+                       if (cookie == desc->async_tx.cookie)
+                               return desc->size;
+               }
+
+               /*
+                * No descriptor found for the cookie, there's thus no residue.
+                * This shouldn't happen if the calling driver passes a correct
+                * cookie value.
+                */
+               WARN(1, "No descriptor for cookie!");
+               return 0;
+       }
 
        /*
         * In descriptor mode the descriptor running pointer is not maintained