linux-kernel - Re: [PATCH] usb: common: usb-conn-gpio: Set last role to unknown before initial detection

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Date:   Wed, 24 May 2023 11:40:15 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Prashanth K <quic_prashk@...cinc.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: common: usb-conn-gpio: Set last role to unknown
 before initial detection

Il 24/05/23 10:54, Prashanth K ha scritto:
> Currently if we bootup a device without cable connected, then
> usb-conn-gpio won't call set_role() since last_role is same as
> current role. This happens because during probe last_role gets
> initialised to zero.
> 
> To avoid this, last_role is set to USB_ROLE_UNKNOWN before
> performing the initial detection.
> 
> Fixes: 4602f3bff266 ("usb: common: add USB GPIO based connection detection driver")
> Signed-off-by: Prashanth K <quic_prashk@...cinc.com>
> ---
>   drivers/usb/common/usb-conn-gpio.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/usb/common/usb-conn-gpio.c b/drivers/usb/common/usb-conn-gpio.c
> index e20874c..00af735 100644
> --- a/drivers/usb/common/usb-conn-gpio.c
> +++ b/drivers/usb/common/usb-conn-gpio.c
> @@ -27,6 +27,8 @@
>   #define USB_CONN_IRQF	\
>   	(IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT)
>   
> +#define USB_ROLE_UNKNOWN	-1

I would add USB_ROLE_UNKNOWN to `enum usb_role` instead.

enum usb_role {
	USB_ROLE_UNKNOWN = -1,
	USB_ROLE_NONE,
	....
};

Regards,
Angelo

> +
>   struct usb_conn_info {
>   	struct device *dev;
>   	struct usb_role_switch *role_sw;
> @@ -257,6 +259,9 @@ static int usb_conn_probe(struct platform_device *pdev)
>   	platform_set_drvdata(pdev, info);
>   	device_set_wakeup_capable(&pdev->dev, true);
>   
> +	/* Set last role to unknown before performing the initial detection */
> +	info->last_role = USB_ROLE_UNKNOWN;
> +
>   	/* Perform initial detection */
>   	usb_conn_queue_dwork(info, 0);
>