drm/radeon/kms: fix dpms state on resume

When suspending, we turn the display hw off, at resume the screen will stay black.
This patch turn it on. Fixes:
https://bugzilla.kernel.org/show_bug.cgi?id=16180

Signed-off-by: Cedric Godin <cedric.godin@skynet.be>
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_device.c

@@ -779,6 +779,7 @@ int radeon_suspend_kms(struct drm_device *dev, pm_message_t state)
 
 int radeon_resume_kms(struct drm_device *dev)
 {
+	struct drm_connector *connector;
 	struct radeon_device *rdev = dev->dev_private;
 
 	if (rdev->powered_down)
@@ -797,6 +798,12 @@ int radeon_resume_kms(struct drm_device *dev)
 	radeon_resume(rdev);
 	radeon_pm_resume(rdev);
 	radeon_restore_bios_scratch_regs(rdev);
+
+	/* turn on display hw */
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+		drm_helper_connector_dpms(connector, DRM_MODE_DPMS_ON);
+	}
+
 	radeon_fbdev_set_suspend(rdev, 0);
 	release_console_sem();