[PATCH v2 2/4] mt76: mt7921s: fix race issue between reset and suspend/resume

[sean.wang at mediatek.com]

From: Sean Wang <sean.wang at mediatek.com>

It is unexpected that the reset work is running simultaneously with
the suspend or resume context and it is possible that reset work is still
running even after mt7921 is suspended if we don't fix the race issue.

Thus, the suspend procedure should be waiting until the reset is completed
at the beginning and ignore the subsequent the reset requests.

In case there is an error that happens during either suspend or resume
handler, we will schedule a reset task to recover the error before
returning the error code to ensure we can immediately fix the error there.

Fixes: ca74b9b907f9 ("mt76: mt7921s: add reset support")
Co-developed-by: YN Chen <YN.Chen at mediatek.com>
Signed-off-by: YN Chen <YN.Chen at mediatek.com>
Signed-off-by: Sean Wang <sean.wang at mediatek.com>
---
v2: use flush_work instead of cancel_work_sync
---
 drivers/net/wireless/mediatek/mt76/mt7921/sdio.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/sdio.c b/drivers/net/wireless/mediatek/mt76/mt7921/sdio.c
index 487acd6e2be8..2face849fb4f 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/sdio.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/sdio.c
@@ -206,6 +206,7 @@ static int mt7921s_suspend(struct device *__dev)
 	pm->suspended = true;
 	set_bit(MT76_STATE_SUSPEND, &mdev->phy.state);
 
+	flush_work(&dev->reset_work);
 	cancel_delayed_work_sync(&pm->ps_work);
 	cancel_work_sync(&pm->wake_work);
 
@@ -261,6 +262,9 @@ static int mt7921s_suspend(struct device *__dev)
 	clear_bit(MT76_STATE_SUSPEND, &mdev->phy.state);
 	pm->suspended = false;
 
+	if (err < 0)
+		mt7921_reset(&dev->mt76);
+
 	return err;
 }
 
@@ -276,7 +280,7 @@ static int mt7921s_resume(struct device *__dev)
 
 	err = mt7921_mcu_drv_pmctrl(dev);
 	if (err < 0)
-		return err;
+		goto failed;
 
 	mt76_worker_enable(&mdev->tx_worker);
 	mt76_worker_enable(&mdev->sdio.txrx_worker);
@@ -288,11 +292,12 @@ static int mt7921s_resume(struct device *__dev)
 		mt76_connac_mcu_set_deep_sleep(mdev, false);
 
 	err = mt76_connac_mcu_set_hif_suspend(mdev, false);
-	if (err)
-		return err;
-
+failed:
 	pm->suspended = false;
 
+	if (err < 0)
+		mt7921_reset(&dev->mt76);
+
 	return err;
 }
 
-- 
2.25.1