linux-kernel - [PATCH] Bluetooth: btusb: Reset port on cmd timeout

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Date:   Wed, 24 Jun 2020 10:58:09 -0700
From:   Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
To:     rjliao@...eaurora.org, marcel@...tmann.org,
        linux-bluetooth@...r.kernel.org
Cc:     chromeos-bluetooth-upstreaming@...omium.org,
        linux-usb@...r.kernel.org, linux-pm@...r.kernel.org,
        Abhishek Pandit-Subedi <abhishekpandit@...omium.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] Bluetooth: btusb: Reset port on cmd timeout

QCA_ROME doesn't have support for the reset gpio but sometimes gets into
a state where it is unresponsive to commands. When this happens, reset
the port to attempt to revive the chip.

Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
---
On Chromebooks with this chipset, we encountered cmd_timeout after
running suspend stress test for hundreds of iterations. Without
a recovery mechanism, continued cmd_timeout failures eventually caused
the suspend stress test to fail.

This change will just reset the port that the Bluetooth chip is on when
cmd_timeout is encountered. At the very least, the driver will unload
and stop affecting suspend. It doesn't seem to restore the BT controller
to a good state however (this still requires a power cycle).

 drivers/bluetooth/btusb.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index e42fdd625eb023..b806a88702328b 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -573,6 +573,22 @@ static void btusb_rtl_cmd_timeout(struct hci_dev *hdev)
 	gpiod_set_value_cansleep(reset_gpio, 0);
 }
 
+static void btusb_generic_usb_cmd_timeout(struct hci_dev *hdev)
+{
+	struct btusb_data *data = hci_get_drvdata(hdev);
+	int err;
+
+	if (++data->cmd_timeout_cnt < 5)
+		return;
+
+	bt_dev_err(hdev, "Multiple cmd timeouts seen. Resetting usb device.");
+	err = usb_autopm_get_interface(data->intf);
+	if (!err)
+		usb_queue_reset_device(data->intf);
+	else
+		bt_dev_err(hdev, "Failed usb_autopm_get_interface with %d", err);
+}
+
 static inline void btusb_free_frags(struct btusb_data *data)
 {
 	unsigned long flags;
@@ -3964,6 +3980,7 @@ static int btusb_probe(struct usb_interface *intf,
 	if (id->driver_info & BTUSB_QCA_ROME) {
 		data->setup_on_usb = btusb_setup_qca;
 		hdev->set_bdaddr = btusb_set_bdaddr_ath3012;
+		hdev->cmd_timeout = btusb_generic_usb_cmd_timeout;
 		set_bit(HCI_QUIRK_SIMULTANEOUS_DISCOVERY, &hdev->quirks);
 		btusb_check_needs_reset_resume(intf);
 	}
-- 
2.27.0.111.gc72c7da667-goog