1 files changed, 9 insertions, 4 deletions

diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index cb058408c70e..cb8cfb7e0974 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -492,6 +492,7 @@ void intel_panel_set_backlight(struct intel_connector *connector, u32 level,
         enum pipe pipe = intel_get_pipe_from_connector(connector);
         u32 freq;
         unsigned long flags;
+        u64 n;
 
         if (!panel->backlight.present || pipe == INVALID_PIPE)
                 return;
@@ -502,10 +503,9 @@ void intel_panel_set_backlight(struct intel_connector *connector, u32 level,
 
         /* scale to hardware max, but be careful to not overflow */
         freq = panel->backlight.max;
-        if (freq < max)
-                level = level * freq / max;
-        else
-                level = freq / max * level;
+        n = (u64)level * freq;
+        do_div(n, max);
+        level = n;
 
         panel->backlight.level = level;
         if (panel->backlight.device)
@@ -1065,6 +1065,11 @@ int intel_panel_setup_backlight(struct drm_connector *connector)
         unsigned long flags;
         int ret;
 
+        if (!dev_priv->vbt.backlight.present) {
+                DRM_DEBUG_KMS("native backlight control not available per VBT\n");
+                return 0;
+        }
+
         /* set level and max in panel struct */
         spin_lock_irqsave(&dev_priv->backlight_lock, flags);
         ret = dev_priv->display.setup_backlight(intel_connector);