[focal:linux-azure][PATCH 13/21] video: hyperv_fb: Fix hibernation for the deferred IO feature

[Marcelo Henrique Cerri]

From: Dexuan Cui <decui at microsoft.com>

BugLink: http://bugs.launchpad.net/bugs/1880032

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>
Reviewed-by: Wei Hu <weh at microsoft.com>
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie at samsung.com>
Signed-off-by: Sasha Levin <sashal at kernel.org>
(cherry picked from commit 382a46221757250966621f046e91d8c05adac12b)
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri at canonical.com>
---
 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 fe4731f97df7..5017b4b20781 100644
--- a/drivers/video/fbdev/hyperv_fb.c
+++ b/drivers/video/fbdev/hyperv_fb.c
@@ -891,6 +891,7 @@ 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;
@@ -924,6 +925,7 @@ 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 */
-- 
2.25.1