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V4L/DVB (7331): Fix em2800 altsetting selection

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Signed-off-by: Sascha Sommer <saschasommer@freenet.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
This commit is contained in:
Sascha Sommer
2008-04-22 14:45:47 -03:00
committed by Mauro Carvalho Chehab
parent 4a24ce3a17
commit 2c4a07b2da
1 changed files with 13 additions and 5 deletions
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18
drivers/media/video/em28xx/em28xx-core.c
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@@ -813,19 +813,27 @@ int em28xx_set_alternate(struct em28xx *dev)
{ {
int errCode, prev_alt = dev->alt; int errCode, prev_alt = dev->alt;
int i; 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 the frame size should be increased, otherwise, only
green screen will be received. green screen will be received.
*/ */
if (dev->frame_size > 720*240*2) if (dev->frame_size > 720*240*2)
min_pkt_size *= 2; min_pkt_size *= 2;
for (i = 0; i < dev->num_alt; i++) for (i = 0; i < dev->num_alt; i++) {
if (dev->alt_max_pkt_size[i] >= min_pkt_size) /* stop when the selected alt setting offers enough bandwidth */
if (dev->alt_max_pkt_size[i] >= min_pkt_size) {
dev->alt = i;
break; 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) { if (dev->alt != prev_alt) {
em28xx_coredbg("minimum isoc packet size: %u (alt=%d)\n", em28xx_coredbg("minimum isoc packet size: %u (alt=%d)\n",