Not all systems expose a firmware or platform mechanism for changing the backlight intensity on i915, so add native driver support.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: David Airlie <airlied@linux.ie>
Cc: Alex Deucher <alexdeucher@gmail.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: Sedat Dilek <sedat.dilek@googlemail.com>
Tested-by: Michel Alexandre Salim <salimma@fedoraproject.org>
Tested-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Keith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/intel_dp.c

@@ -1841,6 +1841,11 @@ done:
 static void
 intel_dp_destroy (struct drm_connector *connector)
 {
+	struct drm_device *dev = connector->dev;
+
+	if (intel_dpd_is_edp(dev))
+		intel_panel_destroy_backlight(dev);
+
 	drm_sysfs_connector_remove(connector);
 	drm_connector_cleanup(connector);
 	kfree(connector);
@@ -2072,6 +2077,8 @@ intel_dp_init(struct drm_device *dev, int output_reg)
 					DRM_MODE_TYPE_PREFERRED;
 			}
 		}
+		dev_priv->int_edp_connector = connector;
+		intel_panel_setup_backlight(dev);
 	}
 
 	intel_dp_add_properties(intel_dp, connector);