[PATCH 1/1][SRU][OEM-5.10] drm/i915: Wait for scanout to stop when sanitizing planes

[Koba Ko]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

BugLink: https://bugs.launchpad.net/bugs/1955692  

When we sanitize planes let's wait for the scanout to stop
before we let the subsequent code tear down the ggtt mappings
and whatnot. Cures an underrun on my ivb when I boot with
VT-d enabled and the BIOS fb gets thrown out due to stolen
being considered unusable with VT-d active.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210217162050.13803-1-ville.syrjala@linux.intel.com
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
(cherry picked from commit 1835bf459df752d13f9fbae37a521a471172d3d1)
Signed-off-by: Koba Ko <koba.ko at canonical.com>
---
 drivers/gpu/drm/i915/display/intel_display.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index a35462277637c..6f538fbe4688e 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -3593,6 +3593,7 @@ static void intel_plane_disable_noatomic(struct intel_crtc *crtc,
 		intel_set_cpu_fifo_underrun_reporting(dev_priv, crtc->pipe, false);
 
 	intel_disable_plane(plane, crtc_state);
+	intel_wait_for_vblank(dev_priv, crtc->pipe);
 }
 
 static struct intel_frontbuffer *
-- 
2.25.1