linux-kernel - Re: [PATCH] Bluetooth: btusb: request wake pin with NOAUTOEN

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Message-ID: <20190222183522.GD223791@google.com>
Date:   Fri, 22 Feb 2019 10:35:22 -0800
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Brian Norris <briannorris@...omium.org>
Cc:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org,
        Rajat Jain <rajatja@...gle.com>,
        Heiko Stuebner <heiko@...ech.de>
Subject: Re: [PATCH] Bluetooth: btusb: request wake pin with NOAUTOEN

On Thu, Feb 21, 2019 at 04:30:51PM -0800, Brian Norris wrote:
> Badly-designed systems might have (for example) active-high wake pins
> that default to high (e.g., because of external pull ups) until they
> have an active firmware which starts driving it low. This can cause an
> interrupt storm in the time between request_irq() and disable_irq().
> 
> We don't support shared interrupts here, so let's just pre-configure the
> interrupt to avoid auto-enabling it.
> 
> Fixes: fd913ef7ce61 ("Bluetooth: btusb: Add out-of-band wakeup support")
> Signed-off-by: Brian Norris <briannorris@...omium.org>
> ---
>  drivers/bluetooth/btusb.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index 4761499db9ee..470ee68555d9 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -2885,6 +2885,7 @@ static int btusb_config_oob_wake(struct hci_dev *hdev)
>  		return 0;
>  	}
>  
> +	irq_set_status_flags(irq, IRQ_NOAUTOEN);
>  	ret = devm_request_irq(&hdev->dev, irq, btusb_oob_wake_handler,
>  			       0, "OOB Wake-on-BT", data);
>  	if (ret) {
> @@ -2899,7 +2900,6 @@ static int btusb_config_oob_wake(struct hci_dev *hdev)
>  	}
>  
>  	data->oob_wake_irq = irq;
> -	disable_irq(irq);
>  	bt_dev_info(hdev, "OOB Wake-on-BT configured at IRQ %u", irq);
>  	return 0;
>  }

Reviewed-by: Matthias Kaehlcke <mka@...omium.org>