linux-kernel - [PATCH] mt76: mt7615: retry if mt7615_mcu

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Date:   Wed, 23 Sep 2020 15:23:03 +0800
From:   Chuanhong Guo <gch981213@...il.com>
To:     linux-wireless@...r.kernel.org
Cc:     Chuanhong Guo <gch981213@...il.com>, Felix Fietkau <nbd@....name>,
        Lorenzo Bianconi <lorenzo.bianconi83@...il.com>,
        Ryder Lee <ryder.lee@...iatek.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Sean Wang <sean.wang@...iatek.com>, netdev@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] mt76: mt7615: retry if mt7615_mcu_init returns -EAGAIN

mt7615_load_patch in mt7615/mcu.c sometimes fails with:
mt7622-wmac 18000000.wmac: Failed to get patch semaphore
and returns -EAGAIN. But this error is returned all the way up to
mt7615_init_work with no actual retrial performed, leaving a
broken wireless phy.
Wait a bit and retry for up to 10 times before giving up.

Signed-off-by: Chuanhong Guo <gch981213@...il.com>
---
On my mt7622 board mt7615_load_patch always fails the first time
and it then succeeded on the first retry added by this patch.
"10 times" is an arbitarily picked value and it'll still leave a
broken phy behind if all 10 retries failed. I don't know if that's
okay. Suggestions are welcome!

 drivers/net/wireless/mediatek/mt76/mt7615/pci_init.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/pci_init.c b/drivers/net/wireless/mediatek/mt76/mt7615/pci_init.c
index 7224a00782115..2272f6bcaafe7 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7615/pci_init.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7615/pci_init.c
@@ -16,8 +16,15 @@ static void mt7615_init_work(struct work_struct *work)
 {
 	struct mt7615_dev *dev = container_of(work, struct mt7615_dev,
 					      mcu_work);
+	int i, ret;
 
-	if (mt7615_mcu_init(dev))
+	ret = mt7615_mcu_init(dev);
+	for (i = 0; (ret == -EAGAIN) && (i < 10); i++) {
+		msleep(200);
+		ret = mt7615_mcu_init(dev);
+	}
+
+	if (ret)
 		return;
 
 	mt7615_mcu_set_eeprom(dev);
-- 
2.26.2