1 files changed, 17 insertions, 3 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index e330e762c360..a4e725c6b8c8 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -289,6 +289,10 @@ void radeon_crtc_handle_vblank(struct radeon_device *rdev, int crtc_id)
         u32 update_pending;
         int vpos, hpos;
 
+        /* can happen during initialization */
+        if (radeon_crtc == NULL)
+                return;
+
         spin_lock_irqsave(&rdev->ddev->event_lock, flags);
         work = radeon_crtc->flip_work;
         if (work == NULL) {
@@ -872,14 +876,14 @@ static void avivo_reduce_ratio(unsigned *nom, unsigned *den,
 
         /* make sure nominator is large enough */
         if (*nom < nom_min) {
-                tmp = (nom_min + *nom - 1) / *nom;
+                tmp = DIV_ROUND_UP(nom_min, *nom);
                 *nom *= tmp;
                 *den *= tmp;
         }
 
         /* make sure the denominator is large enough */
         if (*den < den_min) {
-                tmp = (den_min + *den - 1) / *den;
+                tmp = DIV_ROUND_UP(den_min, *den);
                 *nom *= tmp;
                 *den *= tmp;
         }
@@ -904,7 +908,7 @@ static void avivo_get_fb_ref_div(unsigned nom, unsigned den, unsigned post_div,
                                  unsigned *fb_div, unsigned *ref_div)
 {
         /* limit reference * post divider to a maximum */
-        ref_div_max = min(210 / post_div, ref_div_max);
+        ref_div_max = max(min(100 / post_div, ref_div_max), 1u);
 
         /* get matching reference and feedback divider */
         *ref_div = min(max(DIV_ROUND_CLOSEST(den, post_div), 1u), ref_div_max);
@@ -1039,6 +1043,16 @@ void radeon_compute_pll_avivo(struct radeon_pll *pll,
         /* this also makes sure that the reference divider is large enough */
         avivo_reduce_ratio(&fb_div, &ref_div, fb_div_min, ref_div_min);
 
+        /* avoid high jitter with small fractional dividers */
+        if (pll->flags & RADEON_PLL_USE_FRAC_FB_DIV && (fb_div % 10)) {
+                fb_div_min = max(fb_div_min, (9 - (fb_div % 10)) * 20 + 50);
+                if (fb_div < fb_div_min) {
+                        unsigned tmp = DIV_ROUND_UP(fb_div_min, fb_div);
+                        fb_div *= tmp;
+                        ref_div *= tmp;
+                }
+        }
+
         /* and finally save the result */
         if (pll->flags & RADEON_PLL_USE_FRAC_FB_DIV) {
                 *fb_div_p = fb_div / 10;