linux-kernel - [PATCH v7 2/2] Bluetooth: hci_h5: Add power reset via gpio in h5_btrtl

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Message-Id: <20220126073905.3637841-3-adeep@lexina.in>
Date:   Wed, 26 Jan 2022 10:39:05 +0300
From:   Vyacheslav Bocharov <adeep@...ina.in>
To:     marcel@...tmann.org, johan.hedberg@...il.com, luiz.dentz@...il.com,
        linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Rudi Heitbaum <rudi@...tbaum.com>
Subject: [PATCH v7 2/2] Bluetooth: hci_h5: Add power reset via gpio in h5_btrtl_open

Add power reset for bluetooth via enable-gpios in h5_btrtl_open function.

While testing the RTL8822CS SDIO WiFi/BT adapter, it was found that in
some cases the kernel could not initialize BT firmware. However,
manually resetting the adapter via gpio (off/on sequence) allows it to
start correctly.
Apparently, when the system starts, the adapter is in an undefined state
(including unknown gpio state after starting uboot). A forced reset helps
to initialize the adapter in most cases. It has been found experimentally
that 100 ms is sufficient for a reset.

Signed-off-by: Vyacheslav Bocharov <adeep@...ina.in>
---
 drivers/bluetooth/hci_h5.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/bluetooth/hci_h5.c b/drivers/bluetooth/hci_h5.c
index 34286ffe0568..fdf504b0d265 100644
--- a/drivers/bluetooth/hci_h5.c
+++ b/drivers/bluetooth/hci_h5.c
@@ -966,6 +966,11 @@ static void h5_btrtl_open(struct h5 *h5)
 		pm_runtime_enable(&h5->hu->serdev->dev);
 	}

+	/* The controller needs reset to startup */
+	gpiod_set_value_cansleep(h5->enable_gpio, 0);
+	gpiod_set_value_cansleep(h5->device_wake_gpio, 0);
+	msleep(100);
+
 	/* The controller needs up to 500ms to wakeup */
 	gpiod_set_value_cansleep(h5->enable_gpio, 1);
 	gpiod_set_value_cansleep(h5->device_wake_gpio, 1);
-- 
2.30.2