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Commit 3203f94a authored by Duncan Sands's avatar Duncan Sands Committed by Mauro Carvalho Chehab
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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: default avatarDuncan Sands <baldrick@free.fr>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@infradead.org>
parent faa88df8

drivers/media/video/bt8xx/bttv-risc.c

+6 −8
Original line number Diff line number Diff line
@@ -233,7 +233,7 @@ bttv_risc_overlay(struct bttv *btv, struct btcx_riscmem *risc, 
		  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 @@ bttv_risc_overlay(struct bttv *btv, struct btcx_riscmem *risc, 
	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 @@ bttv_risc_overlay(struct bttv *btv, struct btcx_riscmem *risc, 
		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) {