[PATCH v1 2/2] Bluetooth: btnxpuart: Fix nxp_setup

[Marcel Ziswiler <marcel@ziswiler.com>]

From: Marcel Ziswiler <marcel.ziswiler@toradex.com>

Unfortunately, nxp_setup() may inadvertently assume that the
firmware is already running while the module is not even powered yet.
Fix this by waiting up to 10 seconds for the CTS to go up as the combo
firmware might be loaded by the Wi-Fi driver over SDIO (mwifiex_sdio).

Fixes: 689ca16e5232 ("Bluetooth: NXP: Add protocol support for NXP Bluetooth chipsets")

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>

---
This is what may happen without this fix:
[  284.588177] Bluetooth: hci0: Opcode 0x0c03 failed: -110
[  286.636167] Bluetooth: hci0: Setting wake-up method failed (-110)
Unfortunately, even re-loading the btnxpuart kernel module would not
recover from this condition.

 drivers/bluetooth/btnxpuart.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/bluetooth/btnxpuart.c b/drivers/bluetooth/btnxpuart.c
index 9cb7529eef09..4b83a0aa3459 100644
--- a/drivers/bluetooth/btnxpuart.c
+++ b/drivers/bluetooth/btnxpuart.c
@@ -1021,6 +1021,16 @@ static int nxp_setup(struct hci_dev *hdev)
 		if (err < 0)
 			return err;
 	} else {
+		/* The combo firmware might be loaded by the Wi-Fi driver over SDIO (mwifiex_sdio).
+		 * We wait up to 10s for the CTS to go up. Afterwards, we know that the firmware is
+		 * really ready.
+		 */
+		err = serdev_device_wait_for_cts(nxpdev->serdev, true, 10000);
+		if (err) {
+			bt_dev_err(nxpdev->hdev, "Wait for CTS failed with %d", err);
+			return err;
+		}
+
 		bt_dev_dbg(hdev, "FW already running.");
 		clear_bit(BTNXPUART_FW_DOWNLOADING, &nxpdev->tx_state);
 	}
-- 
2.36.1