drm/i915: Use DIV_ROUND_CLOSEST() to calculate dot/vco

Rounding down when calculating the dot/vco frequencies doesn't make much
sense. Round to closest should give slightly nicer answers.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -329,8 +329,8 @@ static void vlv_clock(int refclk, intel_clock_t *clock)
 {
 	clock->m = clock->m1 * clock->m2;
 	clock->p = clock->p1 * clock->p2;
-	clock->vco = refclk * clock->m / clock->n;
-	clock->dot = clock->vco / clock->p;
+	clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
+	clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
 }
 
 /**
@@ -430,8 +430,8 @@ static void pineview_clock(int refclk, intel_clock_t *clock)
 {
 	clock->m = clock->m2 + 2;
 	clock->p = clock->p1 * clock->p2;
-	clock->vco = refclk * clock->m / clock->n;
-	clock->dot = clock->vco / clock->p;
+	clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
+	clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
 }
 
 static uint32_t i9xx_dpll_compute_m(struct dpll *dpll)
@@ -443,8 +443,8 @@ static void i9xx_clock(int refclk, intel_clock_t *clock)
 {
 	clock->m = i9xx_dpll_compute_m(clock);
 	clock->p = clock->p1 * clock->p2;
-	clock->vco = refclk * clock->m / (clock->n + 2);
-	clock->dot = clock->vco / clock->p;
+	clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n + 2);
+	clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
 }
 
 #define INTELPllInvalid(s)   do { /* DRM_DEBUG(s); */ return false; } while (0)