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Subject: Re: [PATCH v5 4/4] Bluetooth: btusb: Use the cmd_timeout method to
 reset the Intel BT chip
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20190123205725.239661-4-rajatja@google.com>
Date:   Thu, 24 Jan 2019 10:46:30 +0100
Cc:     Johan Hedberg <johan.hedberg@gmail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "David S. Miller" <davem@davemloft.net>,
        Dmitry Torokhov <dtor@chromium.org>,
        Alex Hung <alex.hung@canonical.com>,
        linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-usb@vger.kernel.org, netdev@vger.kernel.org,
        rajatxjain@gmail.com, dtor@google.com, raghuram.hegde@intel.com,
        chethan.tumkur.narayan@intel.com, sukumar.ghorai@intel.com
Content-Transfer-Encoding: 8BIT
Message-Id: <7A112914-5B41-4D26-807B-021B7AC907C6@holtmann.org>
References: <20181117010748.24347-1-rajatja@google.com>
 <20190123205725.239661-1-rajatja@google.com>
 <20190123205725.239661-4-rajatja@google.com>
To:     Rajat Jain <rajatja@google.com>
Sender: linux-bluetooth-owner@vger.kernel.org
Precedence: bulk

Hi Rajat,

> If the platform provides it, use the reset gpio to reset the Intel BT
> chip, as part of cmd_timeout handling. This has been found helpful on
> Intel bluetooth controllers where the firmware gets stuck and the only
> way out is a hard reset pin provided by the platform.
> 
> Signed-off-by: Rajat Jain <rajatja@google.com>
> ---
> v5: Rename the hook to cmd_timeout, and wait for 5 timeouts before
>    resetting the device.
> v4: Use data->flags instead of clearing the quirk in btusb_hw_reset()
> v3: Better error handling for gpiod_get_optional()
> v2: Handle the EPROBE_DEFER case.
> 
> drivers/bluetooth/btusb.c | 54 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 54 insertions(+)
> 
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index 4761499db9ee..8949ea30a1bc 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -29,6 +29,7 @@
> #include <linux/of_device.h>
> #include <linux/of_irq.h>
> #include <linux/suspend.h>
> +#include <linux/gpio/consumer.h>
> #include <asm/unaligned.h>
> 
> #include <net/bluetooth/bluetooth.h>
> @@ -439,6 +440,7 @@ static const struct dmi_system_id btusb_needs_reset_resume_table[] = {
> #define BTUSB_BOOTING		9
> #define BTUSB_DIAG_RUNNING	10
> #define BTUSB_OOB_WAKE_ENABLED	11
> +#define BTUSB_HW_RESET_ACTIVE	12
> 
> struct btusb_data {
> 	struct hci_dev       *hdev;
> @@ -476,6 +478,8 @@ struct btusb_data {
> 	struct usb_endpoint_descriptor *diag_tx_ep;
> 	struct usb_endpoint_descriptor *diag_rx_ep;
> 
> +	struct gpio_desc *reset_gpio;
> +
> 	__u8 cmdreq_type;
> 	__u8 cmdreq;
> 
> @@ -489,8 +493,39 @@ struct btusb_data {
> 	int (*setup_on_usb)(struct hci_dev *hdev);
> 
> 	int oob_wake_irq;   /* irq for out-of-band wake-on-bt */
> +	unsigned num_cmd_timeout;

Make this cmd_timeout_count or cmd_timeout_cnt.

> };
> 
> +
> +static void btusb_intel_cmd_timeout(struct hci_dev *hdev,
> +				    struct hci_command_hdr *cmd)
> +{
> +	struct btusb_data *data = hci_get_drvdata(hdev);
> +	struct gpio_desc *reset_gpio = data->reset_gpio;
> +
> +	bt_dev_err(hdev, "btusb num_cmd_timeout = %u", ++data->num_cmd_timeout);

I would prefer if you don’t do the increase in the bt_dev_err(). And you can also scrap the “btusb “ prefix here since that is all present via bt_dev_err if really needed at some point. Actually I question the whole bt_dev_err here in the first place since the core will put our the error. You are just repeating it here.

> +
> +	if (data->num_cmd_timeout < 5)
> +		return;

So I would propose to do just this:

	if (++data->cmd_timeout_count < 5)
		return;

> +
> +	/*
> +	 * Toggle the hard reset line if the platform provides one. The reset
> +	 * is going to yank the device off the USB and then replug. So doing
> +	 * once is enough. The cleanup is handled correctly on the way out
> +	 * (standard USB disconnect), and the new device is detected cleanly
> +	 * and bound to the driver again like it should be.
> +	 */
> +	if (test_and_set_bit(BTUSB_HW_RESET_ACTIVE, &data->flags)) {
> +		bt_dev_err(hdev, "last reset failed? Not resetting again");
> +		return;
> +	}
> +
> +	bt_dev_err(hdev, "Initiating HW reset via gpio");
> +	gpiod_set_value(reset_gpio, 1);
> +	mdelay(100);
> +	gpiod_set_value(reset_gpio, 0);
> +}
> +
> static inline void btusb_free_frags(struct btusb_data *data)
> {
> 	unsigned long flags;
> @@ -2915,6 +2950,7 @@ static int btusb_probe(struct usb_interface *intf,
> 		       const struct usb_device_id *id)
> {
> 	struct usb_endpoint_descriptor *ep_desc;
> +	struct gpio_desc *reset_gpio;
> 	struct btusb_data *data;
> 	struct hci_dev *hdev;
> 	unsigned ifnum_base;
> @@ -3028,6 +3064,15 @@ static int btusb_probe(struct usb_interface *intf,
> 
> 	SET_HCIDEV_DEV(hdev, &intf->dev);
> 
> +	reset_gpio = gpiod_get_optional(&data->udev->dev, "reset",
> +					GPIOD_OUT_LOW);

Any reason to not use the devm_gpiod_get_optional() version here?

> +	if (IS_ERR(reset_gpio)) {
> +		err = PTR_ERR(reset_gpio);
> +		goto out_free_dev;
> +	} else if (reset_gpio) {
> +		data->reset_gpio = reset_gpio;
> +	}
> +
> 	hdev->open   = btusb_open;
> 	hdev->close  = btusb_close;
> 	hdev->flush  = btusb_flush;
> @@ -3085,6 +3130,8 @@ static int btusb_probe(struct usb_interface *intf,
> 		set_bit(HCI_QUIRK_STRICT_DUPLICATE_FILTER, &hdev->quirks);
> 		set_bit(HCI_QUIRK_SIMULTANEOUS_DISCOVERY, &hdev->quirks);
> 		set_bit(HCI_QUIRK_NON_PERSISTENT_DIAG, &hdev->quirks);
> +		if (data->reset_gpio)
> +			hdev->cmd_timeout = btusb_intel_cmd_timeout;
> 	}

Always assign hdev->cmd_timeout = btusb_intel_cmd_timeout and put it after btintel_set_bdaddr and before the quirks.

Move the if (data->reset_gpio) check into btusb_intel_cmd_timeout() function and print a warning that no reset GPIO is present.

> 
> 	if (id->driver_info & BTUSB_INTEL_NEW) {
> @@ -3097,6 +3144,8 @@ static int btusb_probe(struct usb_interface *intf,
> 		set_bit(HCI_QUIRK_STRICT_DUPLICATE_FILTER, &hdev->quirks);
> 		set_bit(HCI_QUIRK_SIMULTANEOUS_DISCOVERY, &hdev->quirks);
> 		set_bit(HCI_QUIRK_NON_PERSISTENT_DIAG, &hdev->quirks);
> +		if (data->reset_gpio)
> +			hdev->cmd_timeout = btusb_intel_cmd_timeout;
> 	}
> 
> 	if (id->driver_info & BTUSB_MARVELL)
> @@ -3226,6 +3275,8 @@ static int btusb_probe(struct usb_interface *intf,
> 	return 0;
> 
> out_free_dev:
> +	if (data->reset_gpio)
> +		gpiod_put(data->reset_gpio);
> 	hci_free_dev(hdev);
> 	return err;
> }
> @@ -3269,6 +3320,9 @@ static void btusb_disconnect(struct usb_interface *intf)
> 	if (data->oob_wake_irq)
> 		device_init_wakeup(&data->udev->dev, false);
> 
> +	if (data->reset_gpio)
> +		gpiod_put(data->reset_gpio);
> +
> 	hci_free_dev(hdev);
> }

Regards

Marcel