Merge tag 'drm-fixes-2018-10-20-1' of git://anongit.freedesktop.org/drm/drm

Dave writes:
  "drm fixes for 4.19 final (part 2)

   Looked like two stragglers snuck in, one very urgent the pageflipping
   was missing a reference that could result in a GPF on non-i915
   drivers, the other is an overflow in the sun4i dotclock calcs
   resulting in a mode not getting set."

* tag 'drm-fixes-2018-10-20-1' of git://anongit.freedesktop.org/drm/drm:
  drm/sun4i: Fix an ulong overflow in the dotclock driver
  drm: Get ref on CRTC commit object when waiting for flip_done

1 files changed, 11 insertions, 1 deletions

diff --git a/drivers/gpu/drm/sun4i/sun4i_dotclock.c b/drivers/gpu/drm/sun4i/sun4i_dotclock.c
index e36004fbe453..2a15f2f9271e 100644
--- a/drivers/gpu/drm/sun4i/sun4i_dotclock.c
+++ b/drivers/gpu/drm/sun4i/sun4i_dotclock.c
@@ -81,9 +81,19 @@ static long sun4i_dclk_round_rate(struct clk_hw *hw, unsigned long rate,
 	int i;
 
 	for (i = tcon->dclk_min_div; i <= tcon->dclk_max_div; i++) {
-		unsigned long ideal = rate * i;
+		u64 ideal = (u64)rate * i;
 		unsigned long rounded;
 
+		/*
+		 * ideal has overflowed the max value that can be stored in an
+		 * unsigned long, and every clk operation we might do on a
+		 * truncated u64 value will give us incorrect results.
+		 * Let's just stop there since bigger dividers will result in
+		 * the same overflow issue.
+		 */
+		if (ideal > ULONG_MAX)
+			goto out;
+
 		rounded = clk_hw_round_rate(clk_hw_get_parent(hw),
 					    ideal);