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>
diff --git a/drivers/video/intelfb/intelfbhw.c b/drivers/video/intelfb/intelfbhw.c
index c1eb18b..16bc8d7 100644
--- a/drivers/video/intelfb/intelfbhw.c
+++ b/drivers/video/intelfb/intelfbhw.c
@@ -1428,6 +1428,24 @@
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 @@
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 @@
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