linux-kernel - [PATCH v5 2/2] Bluetooth: hci_h5: Add power reset via gpio in h5_btrtl

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Date:   Tue, 25 Jan 2022 19:14:01 +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 v5 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.

Signed-off-by: Vyacheslav Bocharov <adeep@...ina.in>
---

While testing the RTL8822CS SDIO WiFi/BT adapter, I found that in some
cases the kernel could not initialize it. However, manually resetting the
adapter via gpio allows it to start correctly.
Apparently at system start the adapter is in an undefined state (including
the unknown state of gpio after starting uboot). A forced reset helps to
initialize the adapter in most cases. Experimentally it was found that
100ms is enough to reset.

 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