drm/radeon: fix display handling in radeon_gpu_reset

If the display hw was reset or a hard reset was used,
we need to re-init some of the common display hardware as well.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/radeon/radeon_device.c

@@ -1681,6 +1681,7 @@ int radeon_gpu_reset(struct radeon_device *rdev)
 	/* block TTM */
 	resched = ttm_bo_lock_delayed_workqueue(&rdev->mman.bdev);
 	radeon_suspend(rdev);
+	radeon_hpd_fini(rdev);
 
 	for (i = 0; i < RADEON_NUM_RINGS; ++i) {
 		ring_sizes[i] = radeon_ring_backup(rdev, &rdev->ring[i],
@@ -1737,6 +1738,21 @@ retry:
 		radeon_pm_resume(rdev);
 	}
 
+	/* init dig PHYs, disp eng pll */
+	if (rdev->is_atom_bios) {
+		radeon_atom_encoder_init(rdev);
+		radeon_atom_disp_eng_pll_init(rdev);
+		/* turn on the BL */
+		if (rdev->mode_info.bl_encoder) {
+			u8 bl_level = radeon_get_backlight_level(rdev,
+								 rdev->mode_info.bl_encoder);
+			radeon_set_backlight_level(rdev, rdev->mode_info.bl_encoder,
+						   bl_level);
+		}
+	}
+	/* reset hpd state */
+	radeon_hpd_init(rdev);
+
 	drm_helper_resume_force_mode(rdev->ddev);
 
 	/* set the power state here in case we are a PX system or headless */