V4L/DVB (7331): Fix em2800 altsetting selection

Signed-off-by: Sascha Sommer <saschasommer@freenet.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 13 insertions, 5 deletions

diff --git a/drivers/media/video/em28xx/em28xx-core.c b/drivers/media/video/em28xx/em28xx-core.c
index dbea89c115b1..4ebef10b5722 100644
--- a/drivers/media/video/em28xx/em28xx-core.c
+++ b/drivers/media/video/em28xx/em28xx-core.c
@@ -813,19 +813,27 @@ int em28xx_set_alternate(struct em28xx *dev)
 {
         int errCode, prev_alt = dev->alt;
         int i;
-        unsigned int min_pkt_size = dev->bytesperline+4;
+        unsigned int min_pkt_size = dev->bytesperline + 4;
 
-        /* When image size is bigger than a ceirtain value,
+        /* When image size is bigger than a certain value,
            the frame size should be increased, otherwise, only
            green screen will be received.
          */
         if (dev->frame_size > 720*240*2)
                 min_pkt_size *= 2;
 
-        for (i = 0; i < dev->num_alt; i++)
-                if (dev->alt_max_pkt_size[i] >= min_pkt_size)
+        for (i = 0; i < dev->num_alt; i++) {
+                /* stop when the selected alt setting offers enough bandwidth */
+                if (dev->alt_max_pkt_size[i] >= min_pkt_size) {
+                        dev->alt = i;
                         break;
-        dev->alt = i;
+                /* otherwise make sure that we end up with the maximum bandwidth
+                   because the min_pkt_size equation might be wrong...
+                */
+                } else if (dev->alt_max_pkt_size[i] >
+                           dev->alt_max_pkt_size[dev->alt])
+                        dev->alt = i;
+        }
 
         if (dev->alt != prev_alt) {
                 em28xx_coredbg("minimum isoc packet size: %u (alt=%d)\n",