Bluetooth: serdev: hci_ll: Wait for CTS instead of using msleep

When a TI Bluetooth chip is reset, it takes about 100ms for the RTS line of
the chip to deassert. For my use case with a TI CC2560A chip, this delay
was not long enough and caused the local UART to never transmit at all (TI
AM1808 SoC UART2).

We can wait for the CTS signal using serdev_device_wait_for_cts() instead
of trying to guess using msleep().

Also changed the comment to be more informative while we are touching this
code.

Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

diff --git a/drivers/bluetooth/hci_ll.c b/drivers/bluetooth/hci_ll.c
index ce0dd2f164c7ce12b533010752e4ac390cc31f14..447abea2fa04da54350788aaf59ef13e34018505 100644 (file)
--- a/drivers/bluetooth/hci_ll.c
+++ b/drivers/bluetooth/hci_ll.c
@@ -674,11 +674,15 @@ static int ll_setup(struct hci_uart *hu)
        serdev_device_set_flow_control(serdev, true);
 
        do {
-               /* Configure BT_EN to HIGH state */
+               /* Reset the Bluetooth device */
                gpiod_set_value_cansleep(lldev->enable_gpio, 0);
                msleep(5);
                gpiod_set_value_cansleep(lldev->enable_gpio, 1);
-               msleep(100);
+               err = serdev_device_wait_for_cts(serdev, true, 200);
+               if (err) {
+                       bt_dev_err(hu->hdev, "Failed to get CTS");
+                       return err;
+               }
 
                err = download_firmware(lldev);
                if (!err)