linux-kernel - [PATCH v1] Bluetooth: btnxpuart: Revert baudrate change in nxp

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Message-Id: <20250403150223.4136-2-neeraj.sanjaykale@nxp.com>
Date: Thu,  3 Apr 2025 20:32:23 +0530
From: Neeraj Sanjay Kale <neeraj.sanjaykale@....com>
To: marcel@...tmann.org,
	luiz.dentz@...il.com
Cc: linux-bluetooth@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	amitkumar.karwar@....com,
	neeraj.sanjaykale@....com,
	sherry.sun@....com
Subject: [PATCH v1] Bluetooth: btnxpuart: Revert baudrate change in nxp_shutdown

This reverts the change baudrate logic in nxp_shutdown.

Earlier, when the driver was removed, it restored the controller
baudrate to fw_init_baudrate, so that on re-loading the driver, things
work fine.

However, if the driver was removed while hci0 interface is down, the
change baudrate vendor command could not be sent by the driver. When the
driver was re-loaded, host and controller baudrate would be mismatched
and hci initialization would fail. The only way to recover would be to
reboot the system.

This issue was fixed by moving the restore baudrate logic from
nxp_serdev_remove() to nxp_shutdown().

This fix however caused another issue with the command "hciconfig hci0
reset", which makes hci0 DOWN and UP immediately.

Running "bluetoothctl power off" and "bluetoothctl power on" in a tight
loop works fine.

To maintain support for "hciconfig reset" command, the above mentioned fix
is reverted.

Fixes: 6fca6781d19d ("Bluetooth: btnxpuart: Move vendor specific initialization to .post_init")
Signed-off-by: Neeraj Sanjay Kale <neeraj.sanjaykale@....com>
---
 drivers/bluetooth/btnxpuart.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/bluetooth/btnxpuart.c b/drivers/bluetooth/btnxpuart.c
index 96dd098cee98..604ab2bba231 100644
--- a/drivers/bluetooth/btnxpuart.c
+++ b/drivers/bluetooth/btnxpuart.c
@@ -1447,9 +1447,6 @@ static int nxp_shutdown(struct hci_dev *hdev)
 		/* HCI_NXP_IND_RESET command may not returns any response */
 		if (!IS_ERR(skb))
 			kfree_skb(skb);
-	} else if (nxpdev->current_baudrate != nxpdev->fw_init_baudrate) {
-		nxpdev->new_baudrate = nxpdev->fw_init_baudrate;
-		nxp_set_baudrate_cmd(hdev, NULL);
 	}

 	return 0;
@@ -1801,13 +1798,15 @@ static void nxp_serdev_remove(struct serdev_device *serdev)
 		clear_bit(BTNXPUART_FW_DOWNLOADING, &nxpdev->tx_state);
 		wake_up_interruptible(&nxpdev->check_boot_sign_wait_q);
 		wake_up_interruptible(&nxpdev->fw_dnld_done_wait_q);
-	}
-
-	if (test_bit(HCI_RUNNING, &hdev->flags)) {
-		/* Ensure shutdown callback is executed before unregistering, so
-		 * that baudrate is reset to initial value.
+	} else {
+		/* Restore FW baudrate to fw_init_baudrate if changed.
+		 * This will ensure FW baudrate is in sync with
+		 * driver baudrate in case this driver is re-inserted.
 		 */
-		nxp_shutdown(hdev);
+		if (nxpdev->current_baudrate != nxpdev->fw_init_baudrate) {
+			nxpdev->new_baudrate = nxpdev->fw_init_baudrate;
+			nxp_set_baudrate_cmd(hdev, NULL);
+		}
 	}

 	ps_cleanup(nxpdev);
-- 
2.25.1