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/i915_drv.h

@@ -36,6 +36,7 @@
 #include <linux/io-mapping.h>
 #include <linux/i2c.h>
 #include <drm/intel-gtt.h>
+#include <linux/backlight.h>
 
 /* General customization:
  */
@@ -690,6 +691,7 @@ typedef struct drm_i915_private {
 	int child_dev_num;
 	struct child_device_config *child_dev;
 	struct drm_connector *int_lvds_connector;
+	struct drm_connector *int_edp_connector;
 
 	bool mchbar_need_disable;
 
@@ -723,6 +725,8 @@ typedef struct drm_i915_private {
 	/* list of fbdev register on this device */
 	struct intel_fbdev *fbdev;
 
+	struct backlight_device *backlight;
+
 	struct drm_property *broadcast_rgb_property;
 	struct drm_property *force_audio_property;
 

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);

drivers/gpu/drm/i915/intel_drv.h

@@ -297,9 +297,10 @@ extern void intel_pch_panel_fitting(struct drm_device *dev,
 extern u32 intel_panel_get_max_backlight(struct drm_device *dev);
 extern u32 intel_panel_get_backlight(struct drm_device *dev);
 extern void intel_panel_set_backlight(struct drm_device *dev, u32 level);
-extern void intel_panel_setup_backlight(struct drm_device *dev);
+extern int intel_panel_setup_backlight(struct drm_device *dev);
 extern void intel_panel_enable_backlight(struct drm_device *dev);
 extern void intel_panel_disable_backlight(struct drm_device *dev);
+extern void intel_panel_destroy_backlight(struct drm_device *dev);
 extern enum drm_connector_status intel_panel_detect(struct drm_device *dev);
 
 extern void intel_crtc_load_lut(struct drm_crtc *crtc);

drivers/gpu/drm/i915/intel_lvds.c

@@ -552,6 +552,8 @@ static void intel_lvds_destroy(struct drm_connector *connector)
 	struct drm_device *dev = connector->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
+	intel_panel_destroy_backlight(dev);
+
 	if (dev_priv->lid_notifier.notifier_call)
 		acpi_lid_notifier_unregister(&dev_priv->lid_notifier);
 	drm_sysfs_connector_remove(connector);
@@ -1032,6 +1034,9 @@ out:
 	/* keep the LVDS connector */
 	dev_priv->int_lvds_connector = connector;
 	drm_sysfs_connector_add(connector);
+
+	intel_panel_setup_backlight(dev);
+
 	return true;
 
 failed:

drivers/gpu/drm/i915/intel_opregion.c

@@ -227,7 +227,6 @@ void intel_opregion_asle_intr(struct drm_device *dev)
 	asle->aslc = asle_stat;
 }
 
-/* Only present on Ironlake+ */
 void intel_opregion_gse_intr(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;

drivers/gpu/drm/i915/intel_panel.c

@@ -277,7 +277,7 @@ void intel_panel_enable_backlight(struct drm_device *dev)
 	dev_priv->backlight_enabled = true;
 }
 
-void intel_panel_setup_backlight(struct drm_device *dev)
+static void intel_panel_init_backlight(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
@@ -309,3 +309,73 @@ intel_panel_detect(struct drm_device *dev)
 
 	return connector_status_unknown;
 }
+
+#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
+static int intel_panel_update_status(struct backlight_device *bd)
+{
+	struct drm_device *dev = bl_get_data(bd);
+	intel_panel_set_backlight(dev, bd->props.brightness);
+	return 0;
+}
+
+static int intel_panel_get_brightness(struct backlight_device *bd)
+{
+	struct drm_device *dev = bl_get_data(bd);
+	return intel_panel_get_backlight(dev);
+}
+
+static const struct backlight_ops intel_panel_bl_ops = {
+	.update_status = intel_panel_update_status,
+	.get_brightness = intel_panel_get_brightness,
+};
+
+int intel_panel_setup_backlight(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct backlight_properties props;
+	struct drm_connector *connector;
+
+	intel_panel_init_backlight(dev);
+
+	if (dev_priv->int_lvds_connector)
+		connector = dev_priv->int_lvds_connector;
+	else if (dev_priv->int_edp_connector)
+		connector = dev_priv->int_edp_connector;
+	else
+		return -ENODEV;
+
+	props.type = BACKLIGHT_RAW;
+	props.max_brightness = intel_panel_get_max_backlight(dev);
+	dev_priv->backlight =
+		backlight_device_register("intel_backlight",
+					  &connector->kdev, dev,
+					  &intel_panel_bl_ops, &props);
+
+	if (IS_ERR(dev_priv->backlight)) {
+		DRM_ERROR("Failed to register backlight: %ld\n",
+			  PTR_ERR(dev_priv->backlight));
+		dev_priv->backlight = NULL;
+		return -ENODEV;
+	}
+	dev_priv->backlight->props.brightness = intel_panel_get_backlight(dev);
+	return 0;
+}
+
+void intel_panel_destroy_backlight(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	if (dev_priv->backlight)
+		backlight_device_unregister(dev_priv->backlight);
+}
+#else
+int intel_panel_setup_backlight(struct drm_device *dev)
+{
+	intel_panel_init_backlight(dev);
+	return 0;
+}
+
+void intel_panel_destroy_backlight(struct drm_device *dev)
+{
+	return;
+}
+#endif