Bluetooth: btmtksdio: mask out interrupt status

Currently, there is a loop in btmtksdio_txrx_work() which iteratively
executes until the variable int_status is zero.

But the variable int_status should be masked out with the actual interrupt
sources (MTK_REG_CHISR bit 0-15) before we check the loop condition.
Otherwise, RX_PKT_LEN (MTK_REG_CHISR bit 16-31) which is read-only and
unclearable would cause the loop to get stuck on some chipsets like
MT7663s.

Fixes: 26270bc1 ("Bluetooth: btmtksdio: move interrupt service to work")
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/btmtksdio.c

@@ -92,6 +92,7 @@ MODULE_DEVICE_TABLE(sdio, btmtksdio_table);
 #define TX_EMPTY		BIT(2)
 #define TX_FIFO_OVERFLOW	BIT(8)
 #define FW_MAILBOX_INT		BIT(15)
+#define INT_MASK		GENMASK(15, 0)
 #define RX_PKT_LEN		GENMASK(31, 16)
 
 #define MTK_REG_CSICR		0xc0
@@ -565,6 +566,7 @@ static void btmtksdio_txrx_work(struct work_struct *work)
 		 * FIFO.
 		 */
 		sdio_writel(bdev->func, int_status, MTK_REG_CHISR, NULL);
+		int_status &= INT_MASK;
 
 		if ((int_status & FW_MAILBOX_INT) &&
 		    bdev->data->chipid == 0x7921) {