Merge tag 'v3.18-rc7' into drm-next

This fixes a bunch of conflicts prior to merging i915 tree.

Linux 3.18-rc7

Conflicts:
	drivers/gpu/drm/exynos/exynos_drm_drv.c
	drivers/gpu/drm/i915/i915_drv.c
	drivers/gpu/drm/i915/intel_pm.c
	drivers/gpu/drm/tegra/dc.c

1 files changed, 15 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index e18b3f49074c..b001c90312e7 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -1094,12 +1094,25 @@ static u32 get_backlight_min_vbt(struct intel_connector *connector)
 	struct drm_device *dev = connector->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_panel *panel = &connector->panel;
+	int min;
 
 	WARN_ON(panel->backlight.max == 0);
 
+	/*
+	 * XXX: If the vbt value is 255, it makes min equal to max, which leads
+	 * to problems. There are such machines out there. Either our
+	 * interpretation is wrong or the vbt has bogus data. Or both. Safeguard
+	 * against this by letting the minimum be at most (arbitrarily chosen)
+	 * 25% of the max.
+	 */
+	min = clamp_t(int, dev_priv->vbt.backlight.min_brightness, 0, 64);
+	if (min != dev_priv->vbt.backlight.min_brightness) {
+		DRM_DEBUG_KMS("clamping VBT min backlight %d/255 to %d/255\n",
+			      dev_priv->vbt.backlight.min_brightness, min);
+	}
+
 	/* vbt value is a coefficient in range [0..255] */
-	return scale(dev_priv->vbt.backlight.min_brightness, 0, 255,
-		     0, panel->backlight.max);
+	return scale(min, 0, 255, 0, panel->backlight.max);
 }
 
 static int bdw_setup_backlight(struct intel_connector *connector)