linux-kernel - [PATCH v4] Bluetooth: btusb: mediatek: fix WMT failure during runtime suspend

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Date:   Thu, 4 Aug 2022 08:45:11 +0800
From:   <sean.wang@...iatek.com>
To:     <marcel@...tmann.org>, <johan.hedberg@...il.com>,
        <luiz.dentz@...il.com>
CC:     <sean.wang@...iatek.com>, <Soul.Huang@...iatek.com>,
        <YN.Chen@...iatek.com>, <Leon.Yen@...iatek.com>,
        <Eric-SY.Chang@...iatek.com>, <Deren.Wu@...iatek.com>,
        <km.lin@...iatek.com>, <robin.chiu@...iatek.com>,
        <Eddie.Chen@...iatek.com>, <ch.yeh@...iatek.com>,
        <posh.sun@...iatek.com>, <ted.huang@...iatek.com>,
        <Stella.Chang@...iatek.com>, <Tom.Chou@...iatek.com>,
        <steve.lee@...iatek.com>, <jsiuda@...gle.com>,
        <frankgor@...gle.com>, <abhishekpandit@...gle.com>,
        <michaelfsun@...gle.com>, <mcchou@...omium.org>,
        <shawnku@...gle.com>, <linux-bluetooth@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, Jing Cai <jing.cai@...iatek.com>
Subject: [PATCH v4] Bluetooth: btusb: mediatek: fix WMT failure during runtime suspend

From: Sean Wang <sean.wang@...iatek.com>

WMT cmd/event doesn't follow up the generic HCI cmd/event handling, it
needs constantly polling control pipe until the host received the WMT
event, thus, we should require to specifically acquire PM counter on the
USB to prevent the interface from entering auto suspended while WMT
cmd/event in progress.

Fixes: a1c49c434e15 ("Bluetooth: btusb: Add protocol support for MediaTek
 MT7668U USB devices")
Co-developed-by: Jing Cai <jing.cai@...iatek.com>
Signed-off-by: Jing Cai <jing.cai@...iatek.com>
Signed-off-by: Sean Wang <sean.wang@...iatek.com>
---
v2:
1. move usb_autopm_[get, put]_interface to btusb_mtk_hci_wmt_sync whenever
wmt cmd is invoked.
2. add the explanation why we needed the specific
usb_autopm_[get, put]_interface there.

v3: correct the version and there is no logic changed
v4: fix GitLint fail due to Title exceeds max length
---
 drivers/bluetooth/btusb.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index e25fcd49db70..449b0a474cca 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -2436,15 +2436,29 @@ static int btusb_mtk_hci_wmt_sync(struct hci_dev
 *hdev,
 
 	set_bit(BTUSB_TX_WAIT_VND_EVT, &data->flags);
 
+	/* WMT cmd/event doesn't follow up the generic HCI cmd/event handling,
+	 * it needs constantly polling control pipe until the host received the
+	 * WMT event, thus, we should require to specifically acquire PM counter
+	 * on the USB to prevent the interface from entering auto suspended
+	 * while WMT cmd/event in progress.
+	 */
+	err = usb_autopm_get_interface(data->intf);
+	if (err < 0)
+		goto err_free_wc;
+
 	err = __hci_cmd_send(hdev, 0xfc6f, hlen, wc);
 
 	if (err < 0) {
 		clear_bit(BTUSB_TX_WAIT_VND_EVT, &data->flags);
+		usb_autopm_put_interface(data->intf);
 		goto err_free_wc;
 	}
 
 	/* Submit control IN URB on demand to process the WMT event */
 	err = btusb_mtk_submit_wmt_recv_urb(hdev);
+
+	usb_autopm_put_interface(data->intf);
+
 	if (err < 0)
 		goto err_free_wc;
 
-- 
2.25.1