drm/i915: avoid brightness overflow when doing scale

[linux-imx.git] / drivers / gpu / drm / i915 / intel_panel.c

diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 67e2c1f1c9a8309b809c35f32395e26e67236992..5063eadac3ef5fc1a2966ccb081ae4bc2aaf8ad1 100644 (file)
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -497,8 +497,11 @@ void intel_panel_set_backlight(struct drm_device *dev, u32 level, u32 max)
                goto out;
        }
 
-       /* scale to hardware */
-       level = level * freq / max;
+       /* scale to hardware, but be careful to not overflow */
+       if (freq < max)
+               level = level * freq / max;
+       else
+               level = freq / max * level;
 
        dev_priv->backlight.level = level;
        if (dev_priv->backlight.device)