[PATCH 44/44] drm/i915/fbdev: Flush mode configuration before lastclose

[Chris Wilson]

During lastclose, we call intel_fbdev_restore_mode() to switch back to
the fbcon configuration on return to VT. However, if we have not yet
finished the asynchronous fbdev initialisation, the current mode will be
invalid and trigger WARNs upon application.

Serialise with the outstanding initialisation if the first application
exits quickly. Note that to hit this in practice requires using an
unregistered async_domain as otherwise modprobe will force a full
synchronisation prior to init() completing.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_fbdev.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
index 638e420a59cb..a19d621d8815 100644
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -830,6 +830,11 @@ void intel_fbdev_restore_mode(struct drm_device *dev)
 	if (!ifbdev)
 		return;
 
+	if (ifbdev->cookie) {
+		async_synchronize_cookie(ifbdev->cookie + 1);
+		ifbdev->cookie = 0;
+	}
+
 	fb_helper = &ifbdev->helper;
 
 	ret = drm_fb_helper_restore_fbdev_mode_unlocked(fb_helper);
-- 
2.8.1