drm/i915/dsi: Group MIPI_SEQ_BACKLIGHT_ON/OFF with panel_[en|dis]able_backlight

Execute the MIPI_SEQ_BACKLIGHT_ON/OFF VBT sequences at the same time as
we call intel_panel_enable_backlight() / intel_panel_disable_backlight().
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Bob Paauwe <bob.j.paauwe@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1488374106-4949-7-git-send-email-jani.nikula@intel.com

drivers/gpu/drm/i915/intel_dsi.c

@@ -829,12 +829,12 @@ static void intel_dsi_pre_enable(struct intel_encoder *encoder,
 		msleep(100);
 
 		intel_dsi_exec_vbt_sequence(intel_dsi, MIPI_SEQ_DISPLAY_ON);
-		intel_dsi_exec_vbt_sequence(intel_dsi, MIPI_SEQ_BACKLIGHT_ON);
 
 		intel_dsi_port_enable(encoder);
 	}
 
 	intel_panel_enable_backlight(intel_dsi->attached_connector);
+	intel_dsi_exec_vbt_sequence(intel_dsi, MIPI_SEQ_BACKLIGHT_ON);
 }
 
 static void intel_dsi_enable_nop(struct intel_encoder *encoder,
@@ -860,6 +860,7 @@ static void intel_dsi_pre_disable(struct intel_encoder *encoder,
 
 	DRM_DEBUG_KMS("\n");
 
+	intel_dsi_exec_vbt_sequence(intel_dsi, MIPI_SEQ_BACKLIGHT_OFF);
 	intel_panel_disable_backlight(intel_dsi->attached_connector);
 
 	/*
@@ -915,7 +916,6 @@ static void intel_dsi_post_disable(struct intel_encoder *encoder,
 	 * if disable packets are sent before sending shutdown packet then in
 	 * some next enable sequence send turn on packet error is observed
 	 */
-	intel_dsi_exec_vbt_sequence(intel_dsi, MIPI_SEQ_BACKLIGHT_OFF);
 	intel_dsi_exec_vbt_sequence(intel_dsi, MIPI_SEQ_DISPLAY_OFF);
 
 	/* Transition to LP-00 */