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intelfb: fix ring space calculation 

If there is less than RING_MIN_FREE available in the ring buffer,
dinfo->ring_space is set to a big value forcing wait_ring to return.

Fix by making ring space = 0 if ring space < RING_MIN_FREE.

Signed-off-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Orczykowski, Juergen 2007-05-08 00:37:25 -07:00 committed by Linus Torvalds
parent 33a9f640a2
commit 71c6efd993
1 changed files with 21 additions and 13 deletions
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34
drivers/video/intelfb/intelfbhw.c
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@ -1428,6 +1428,24 @@ static void refresh_ring(struct intelfb_info *dinfo);
static void reset_state(struct intelfb_info *dinfo);
static void do_flush(struct intelfb_info *dinfo);
static u32 get_ring_space(struct intelfb_info *dinfo)
{
u32 ring_space;
if (dinfo->ring_tail >= dinfo->ring_head)
ring_space = dinfo->ring.size -
(dinfo->ring_tail - dinfo->ring_head);
else
ring_space = dinfo->ring_head - dinfo->ring_tail;
if (ring_space > RING_MIN_FREE)
ring_space -= RING_MIN_FREE;
else
ring_space = 0;
return ring_space;
}
static int
wait_ring(struct intelfb_info *dinfo, int n)
{
@ -1442,13 +1460,8 @@ wait_ring(struct intelfb_info *dinfo, int n)
end = jiffies + (HZ * 3);
while (dinfo->ring_space < n) {
dinfo->ring_head = INREG(PRI_RING_HEAD) & RING_HEAD_MASK;
if (dinfo->ring_tail + RING_MIN_FREE < dinfo->ring_head)
dinfo->ring_space = dinfo->ring_head
- (dinfo->ring_tail + RING_MIN_FREE);
else
dinfo->ring_space = (dinfo->ring.size +
dinfo->ring_head)
- (dinfo->ring_tail + RING_MIN_FREE);
dinfo->ring_space = get_ring_space(dinfo);
if (dinfo->ring_head != last_head) {
end = jiffies + (HZ * 3);
last_head = dinfo->ring_head;
@ -1513,12 +1526,7 @@ refresh_ring(struct intelfb_info *dinfo)
dinfo->ring_head = INREG(PRI_RING_HEAD) & RING_HEAD_MASK;
dinfo->ring_tail = INREG(PRI_RING_TAIL) & RING_TAIL_MASK;
if (dinfo->ring_tail + RING_MIN_FREE < dinfo->ring_head)
dinfo->ring_space = dinfo->ring_head
- (dinfo->ring_tail + RING_MIN_FREE);
else
dinfo->ring_space = (dinfo->ring.size + dinfo->ring_head)
- (dinfo->ring_tail + RING_MIN_FREE);
dinfo->ring_space = get_ring_space(dinfo);
}
static void