If the patch above doesn't work, try this one:Hi Alex,
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 6f56676..a9e0c7b 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -262,6 +262,8 @@ void intel_panel_disable_backlight(struct drm_device *dev)
dev_priv->backlight_level = intel_panel_get_backlight(dev);
dev_priv->backlight_enabled = false;
}
+
+ intel_panel_set_backlight(dev, 0);
}
void intel_panel_enable_backlight(struct drm_device *dev)