V4L/DVB (11323): pxa-camera: simplify the .buf_queue path by merging two loops

pxa_dma_update_sg_tail() is called only once, runs exactly the same loop as the
caller and has to recalculate the last element in an sg-list, that the caller
has already calculated. Eliminate redundancy by merging the two loops and
re-using the calculated pointer. This also saves a bit of performance which is
always good during video-capture.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 6 insertions, 14 deletions

diff --git a/drivers/media/video/pxa_camera.c b/drivers/media/video/pxa_camera.c
index cfa113cedd3e..c639845460ff 100644
--- a/drivers/media/video/pxa_camera.c
+++ b/drivers/media/video/pxa_camera.c
@@ -566,15 +566,6 @@ static void pxa_dma_stop_channels(struct pxa_camera_dev *pcdev)
         }
 }
 
-static void pxa_dma_update_sg_tail(struct pxa_camera_dev *pcdev,
-                                   struct pxa_buffer *buf)
-{
-        int i;
-
-        for (i = 0; i < pcdev->channels; i++)
-                pcdev->sg_tail[i] = buf->dmas[i].sg_cpu + buf->dmas[i].sglen;
-}
-
 static void pxa_dma_add_tail_buf(struct pxa_camera_dev *pcdev,
                                  struct pxa_buffer *buf)
 {
@@ -585,12 +576,13 @@ static void pxa_dma_add_tail_buf(struct pxa_camera_dev *pcdev,
                 buf_last_desc = buf->dmas[i].sg_cpu + buf->dmas[i].sglen;
                 buf_last_desc->ddadr = DDADR_STOP;
 
-                if (!pcdev->sg_tail[i])
-                        continue;
-                pcdev->sg_tail[i]->ddadr = buf->dmas[i].sg_dma;
-        }
+                if (pcdev->sg_tail[i])
+                        /* Link the new buffer to the old tail */
+                        pcdev->sg_tail[i]->ddadr = buf->dmas[i].sg_dma;
 
-        pxa_dma_update_sg_tail(pcdev, buf);
+                /* Update the channel tail */
+                pcdev->sg_tail[i] = buf_last_desc;
+        }
 }
 
 /**