V4L/DVB (3704): Fix some errors on bttv_risc_overlay
There are tree mistakes on bttv_risc_overlay.
1) When skip_odd is true, the number of lines for which
instructions are written is (height+1)/2, not height/2.
2) This occurs when clipping: the number of instruction bytes
written can be as much as 8 + 12*nclips, not 8 + 8*nclips, as
currently estimated.
3) Coverity check were wrong with nskips=0, since it means that
it can clipped at most one line.
Signed-off-by: Duncan Sands <baldrick@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/drivers/media/video/bt8xx/bttv-risc.c b/drivers/media/video/bt8xx/bttv-risc.c
index 16323a5..afcfe71 100644
--- a/drivers/media/video/bt8xx/bttv-risc.c
+++ b/drivers/media/video/bt8xx/bttv-risc.c
@@ -233,7 +233,7 @@
const struct bttv_format *fmt, struct bttv_overlay *ov,
int skip_even, int skip_odd)
{
- int instructions,rc,line,maxy,start,end,skip,nskips;
+ int dwords,rc,line,maxy,start,end,skip,nskips;
struct btcx_skiplist *skips;
u32 *rp,ri,ra;
u32 addr;
@@ -242,12 +242,12 @@
if (NULL == (skips = kmalloc(sizeof(*skips) * ov->nclips,GFP_KERNEL)))
return -ENOMEM;
- /* estimate risc mem: worst case is (clip+1) * lines instructions
+ /* estimate risc mem: worst case is (1.5*clip+1) * lines instructions
+ sync + jump (all 2 dwords) */
- instructions = (ov->nclips + 1) *
- ((skip_even || skip_odd) ? ov->w.height>>1 : ov->w.height);
- instructions += 2;
- if ((rc = btcx_riscmem_alloc(btv->c.pci,risc,instructions*8)) < 0) {
+ dwords = (3 * ov->nclips + 2) *
+ ((skip_even || skip_odd) ? (ov->w.height+1)>>1 : ov->w.height);
+ dwords += 4;
+ if ((rc = btcx_riscmem_alloc(btv->c.pci,risc,dwords*4)) < 0) {
kfree(skips);
return rc;
}
@@ -276,8 +276,6 @@
if (line > maxy)
btcx_calc_skips(line, ov->w.width, &maxy,
skips, &nskips, ov->clips, ov->nclips);
- else
- nskips = 0;
/* write out risc code */
for (start = 0, skip = 0; start < ov->w.width; start = end) {