[PATCH] video: hyperv_fb: Fix hibernation for the deferred IO feature

[Dexuan Cui]

fb_deferred_io_work() can access the vmbus ringbuffer by calling
fbdefio->deferred_io() -> synthvid_deferred_io() -> synthvid_update().

Because the vmbus ringbuffer is inaccessible between hvfb_suspend()
and hvfb_resume(), we must cancel info->deferred_work before calling
vmbus_close() and then reschedule it after we reopen the channel
in hvfb_resume().

Fixes: a4ddb11d297e ("video: hyperv: hyperv_fb: Support deferred IO for Hyper-V frame buffer driver")
Fixes: 824946a8b6fb ("video: hyperv_fb: Add the support of hibernation")
Signed-off-by: Dexuan Cui <decui at microsoft.com>
---

This patch fixes the 2 aforementioned patches on Sasha Levin's Hyper-V tree's
hyperv-next branch:
https://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git/log/?h=hyperv-next

The 2 aforementioned patches have not appeared in the mainline yet, so
please pick up this patch onto he same hyperv-next branch.

 drivers/video/fbdev/hyperv_fb.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
index 4cd27e5172a1..08bc0dfb5ce7 100644
--- a/drivers/video/fbdev/hyperv_fb.c
+++ b/drivers/video/fbdev/hyperv_fb.c
@@ -1194,6 +1194,7 @@ static int hvfb_suspend(struct hv_device *hdev)
 	fb_set_suspend(info, 1);
 
 	cancel_delayed_work_sync(&par->dwork);
+	cancel_delayed_work_sync(&info->deferred_work);
 
 	par->update_saved = par->update;
 	par->update = false;
@@ -1227,6 +1228,7 @@ static int hvfb_resume(struct hv_device *hdev)
 	par->fb_ready = true;
 	par->update = par->update_saved;
 
+	schedule_delayed_work(&info->deferred_work, info->fbdefio->delay);
 	schedule_delayed_work(&par->dwork, HVFB_UPDATE_DELAY);
 
 	/* 0 means do resume */
-- 
2.19.1