linux-kernel - Re: [PATCH] Bluetooth: btusb: Introduce generic USB reset

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Date:   Tue, 4 Oct 2022 13:53:15 -0700
From:   Luiz Augusto von Dentz <luiz.dentz@...il.com>
To:     Archie Pusaka <apusaka@...gle.com>
Cc:     linux-bluetooth <linux-bluetooth@...r.kernel.org>,
        Marcel Holtmann <marcel@...tmann.org>,
        CrosBT Upstreaming <chromeos-bluetooth-upstreaming@...omium.org>,
        Archie Pusaka <apusaka@...omium.org>,
        Abhishek Pandit-Subedi <abhishekpandit@...gle.com>,
        Ying Hsu <yinghsu@...omium.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Bluetooth: btusb: Introduce generic USB reset

Hi Archie,

On Tue, Oct 4, 2022 at 1:33 AM Archie Pusaka <apusaka@...gle.com> wrote:
>
> From: Archie Pusaka <apusaka@...omium.org>
>
> On cmd_timeout and there is no reset_gpio, reset the USB port as a
> last resort.
>
> Signed-off-by: Archie Pusaka <apusaka@...omium.org>
> Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@...gle.com>
> Reviewed-by: Ying Hsu <yinghsu@...omium.org>
>
> ---
>
>  drivers/bluetooth/btusb.c | 26 ++++++++++++++++----------
>  1 file changed, 16 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index 271963805a38..11040124ef79 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -696,6 +696,19 @@ struct btusb_data {
>         unsigned cmd_timeout_cnt;
>  };
>
> +static void generic_usb_reset(struct hci_dev *hdev, struct btusb_data *data)
> +{
> +       int err;
> +
> +       bt_dev_err(hdev, "Resetting usb device.");
> +       /* This is not an unbalanced PM reference since the device will reset */
> +       err = usb_autopm_get_interface(data->intf);
> +       if (!err)
> +               usb_queue_reset_device(data->intf);
> +       else
> +               bt_dev_err(hdev, "Failed usb_autopm_get_interface: %d", err);

Lets just have one line printed if it fails:

err = usb_autopm_get_interface(data->intf);
if (err) {
        bt_dev_err(hdev, "Failed usb_autopm_get_interface: %d", err);
        return;
}

bt_dev_err(hdev, "Resetting usb device.");
usb_queue_reset_device(data->intf);

> +}
> +
>  static void btusb_intel_cmd_timeout(struct hci_dev *hdev)
>  {
>         struct btusb_data *data = hci_get_drvdata(hdev);
> @@ -705,7 +718,7 @@ static void btusb_intel_cmd_timeout(struct hci_dev *hdev)
>                 return;
>
>         if (!reset_gpio) {
> -               bt_dev_err(hdev, "No way to reset. Ignoring and continuing");
> +               generic_usb_reset(hdev, data);

Lets call it btusb_reset since this is specific for the data->intf,
btw is this safe, or perhaps we want to refactor this to have it
callback based so each vendor can add it own specific hdev->reset
callback hardware reset with btusb_reset serving as default callback?
Also the logic of btusb_intel_cmd_timeout should probably be put
inside btintel.c and I don't think we need the gpio_desc reference to
be inside the btusb_data since we can call gpiod_get_optional during
the reset phase and immediately do gpiod_put after done using it.

>                 return;
>         }
>
> @@ -736,7 +749,7 @@ static void btusb_rtl_cmd_timeout(struct hci_dev *hdev)
>                 return;
>
>         if (!reset_gpio) {
> -               bt_dev_err(hdev, "No gpio to reset Realtek device, ignoring");
> +               generic_usb_reset(hdev, data);
>                 return;
>         }
>
> @@ -761,7 +774,6 @@ static void btusb_qca_cmd_timeout(struct hci_dev *hdev)
>  {
>         struct btusb_data *data = hci_get_drvdata(hdev);
>         struct gpio_desc *reset_gpio = data->reset_gpio;
> -       int err;
>
>         if (++data->cmd_timeout_cnt < 5)
>                 return;
> @@ -787,13 +799,7 @@ static void btusb_qca_cmd_timeout(struct hci_dev *hdev)
>                 return;
>         }
>
> -       bt_dev_err(hdev, "Multiple cmd timeouts seen. Resetting usb device.");
> -       /* This is not an unbalanced PM reference since the device will reset */
> -       err = usb_autopm_get_interface(data->intf);
> -       if (!err)
> -               usb_queue_reset_device(data->intf);
> -       else
> -               bt_dev_err(hdev, "Failed usb_autopm_get_interface with %d", err);
> +       generic_usb_reset(hdev, data);
>  }
>
>  static inline void btusb_free_frags(struct btusb_data *data)
> --
> 2.38.0.rc1.362.ged0d419d3c-goog
>


-- 
Luiz Augusto von Dentz