drm/i915/backlight: Restore backlight on resume, v3.

Restore our saved values for backlight. This way even with fastset on
S4 resume we will correctly restore the backlight to the active values.

Changes since v1:
- Call enable_backlight() when backlight.level is set. On suspend
  backlight.enabled is always cleared, this makes it not a good
  indicator. Also check for crtc->state->active.
Changes since v2:
- Use the new update_pipe() callback to run this on resume as well.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Tolga Cakir <cevelnet@gmail.com>
Cc: Basil Eric Rabi <ericbasil.rabi@gmail.com>
Cc: Hans de Goede <jwrdegoede@fedoraproject.org>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190108160842.13396-1-maarten.lankhorst@linux.intel.com

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
index 815ed463d9c5..b4aa49768e90 100644
--- a/drivers/gpu/drm/i915/intel_lvds.c
+++ b/drivers/gpu/drm/i915/intel_lvds.c
@@ -887,6 +887,7 @@ void intel_lvds_init(struct drm_i915_private *dev_priv)
 	}
 	intel_encoder->get_hw_state = intel_lvds_get_hw_state;
 	intel_encoder->get_config = intel_lvds_get_config;
+	intel_encoder->update_pipe = intel_panel_update_backlight;
 	intel_connector->get_hw_state = intel_connector_get_hw_state;
 
 	intel_connector_attach_encoder(intel_connector, intel_encoder);