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Subject: Re: [PATCH] Bluetooth: btusb: Fix suspend issue for Realtek
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20190726115208.GA8152@toshiba>
Date:   Tue, 30 Jul 2019 11:38:51 +0200
Cc:     Johan Hedberg <johan.hedberg@gmail.com>,
        linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org,
        Max Chou <max.chou@realtek.com>
Content-Transfer-Encoding: 8BIT
Message-Id: <C646B2DB-2CC8-4C03-8AAE-7494DD8A3099@holtmann.org>
References: <20190726115208.GA8152@toshiba>
To:     Alex Lu <alex_lu@realsil.com.cn>
Sender: linux-bluetooth-owner@vger.kernel.org
Precedence: bulk

Hi Alex,

> From the perspective of controller, global suspend means there is no
> SET_FEATURE (DEVICE_REMOTE_WAKEUP) and controller would drop the
> firmware. It would consume less power. So we should not send this kind
> of SET_FEATURE when host goes to suspend state.
> Otherwise, when making device enter selective suspend, host should send
> SET_FEATURE to make sure the firmware remains.
> 
> Signed-off-by: Alex Lu <alex_lu@realsil.com.cn>
> ---
> drivers/bluetooth/btusb.c | 40 +++++++++++++++++++++++++++++++++++----
> 1 file changed, 36 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index 50aed5259c2b..69f6b4208901 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -426,6 +426,7 @@ static const struct dmi_system_id btusb_needs_reset_resume_table[] = {
> #define BTUSB_DIAG_RUNNING	10
> #define BTUSB_OOB_WAKE_ENABLED	11
> #define BTUSB_HW_RESET_ACTIVE	12
> +#define BTUSB_QUIRK_SUSPEND	13

I think this name is not really descriptive. What about BTUSB_SUSPEND_DISABLE or BTUSB_WAKEUP_DISABLE or BTUSB_REMOTE_WAKEUP or something that is rather clear.

> 
> struct btusb_data {
> 	struct hci_dev       *hdev;
> @@ -1165,6 +1166,15 @@ static int btusb_open(struct hci_dev *hdev)
> 	 */
> 	device_wakeup_enable(&data->udev->dev);
> 
> +	/* Disable device remote wakeup when host is suspended
> +	 * For Realtek chips, global suspend without
> +	 * SET_FEATURE (DEVICE_REMOTE_WAKEUP) can save more power in device.
> +	 */
> +#ifdef CONFIG_BT_HCIBTUSB_RTL
> +	if (test_bit(BTUSB_QUIRK_SUSPEND, &data->flags))
> +		device_wakeup_disable(&data->udev->dev);
> +#endif
> +

I have no idea what the #ifdef does here. Limiting it to HCIBTUSB_RTL seems pointless.

> 	if (test_and_set_bit(BTUSB_INTR_RUNNING, &data->flags))
> 		goto done;
> 
> @@ -1227,6 +1237,13 @@ static int btusb_close(struct hci_dev *hdev)
> 		goto failed;
> 
> 	data->intf->needs_remote_wakeup = 0;
> +
> +	/* Enable remote wake up for auto-suspend */
> +#ifdef CONFIG_BT_HCIBTUSB_RTL
> +	if (test_bit(BTUSB_QUIRK_SUSPEND, &data->flags))
> +		data->intf->needs_remote_wakeup = 1;
> +#endif
> +

Same comment as above. No need for the #ifdef.

> 	device_wakeup_disable(&data->udev->dev);
> 	usb_autopm_put_interface(data->intf);
> 
> @@ -3185,11 +3202,11 @@ static int btusb_probe(struct usb_interface *intf,
> 	if (id->driver_info & BTUSB_REALTEK) {
> 		hdev->setup = btrtl_setup_realtek;
> 
> -		/* Realtek devices lose their updated firmware over suspend,
> -		 * but the USB hub doesn't notice any status change.
> -		 * Explicitly request a device reset on resume.
> +		/* Realtek devices lose their updated firmware over global
> +		 * suspend that means host doesn't send SET_FEATURE
> +		 * (DEVICE_REMOTE_WAKEUP)
> 		 */
> -		interface_to_usbdev(intf)->quirks |= USB_QUIRK_RESET_RESUME;
> +		set_bit(BTUSB_QUIRK_SUSPEND, &data->flags);
> 	}
> #endif
> 
> @@ -3363,6 +3380,21 @@ static int btusb_suspend(struct usb_interface *intf, pm_message_t message)
> 		enable_irq(data->oob_wake_irq);
> 	}
> 
> +#ifdef CONFIG_BT_HCIBTUSB_RTL
> +	/* For global suspend, Realtek devices lose the loaded fw
> +	 * in them. But for autosuspend, firmware should remain.
> +	 * Actually, it depends on whether the usb host sends
> +	 * set feature (enable wakeup) or not.
> +	 */
> +	if (test_bit(BTUSB_QUIRK_SUSPEND, &data->flags)) {
> +		if (PMSG_IS_AUTO(message) &&
> +		    device_can_wakeup(&data->udev->dev))
> +			data->udev->do_remote_wakeup = 1;
> +		else if (!PMSG_IS_AUTO(message))
> +			data->udev->reset_resume = 1;
> +	}
> +#endif
> +

The #ifdef is also not needed here.

Regards

Marcel