linux-kernel - Re: usb: common: usb-conn-gpio: Prevent bailing out if initial role is none

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Message-ID: <2023072517-revocable-squiggly-de1c@gregkh>
Date:   Tue, 25 Jul 2023 17:34:03 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Prashanth K <quic_prashk@...cinc.com>
Cc:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: usb: common: usb-conn-gpio: Prevent bailing out if initial role
 is none

On Thu, Jul 06, 2023 at 03:40:58PM +0530, Prashanth K wrote:
> 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, add a new flag initial_det in usb_conn_info,
> which is used to prevent bailing out during init 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 | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/common/usb-conn-gpio.c b/drivers/usb/common/usb-conn-gpio.c
> index 766005d..46290ff 100644
> --- a/drivers/usb/common/usb-conn-gpio.c
> +++ b/drivers/usb/common/usb-conn-gpio.c
> @@ -42,6 +42,7 @@ struct usb_conn_info {
>  
>  	struct power_supply_desc desc;
>  	struct power_supply *charger;
> +	bool initial_det;

What does "initial_det" mean?  Please document this better.

>  };
>  
>  /*
> @@ -86,11 +87,13 @@ static void usb_conn_detect_cable(struct work_struct *work)
>  	dev_dbg(info->dev, "role %s -> %s, gpios: id %d, vbus %d\n",
>  		usb_role_string(info->last_role), usb_role_string(role), id, vbus);
>  
> -	if (info->last_role == role) {
> +	if (!info->initial_det && info->last_role == role) {
>  		dev_warn(info->dev, "repeated role: %s\n", usb_role_string(role));
>  		return;
>  	}
>  
> +	info->initial_det = false;
> +
>  	if (info->last_role == USB_ROLE_HOST && info->vbus)
>  		regulator_disable(info->vbus);
>  
> @@ -258,6 +261,7 @@ static int usb_conn_probe(struct platform_device *pdev)
>  	device_set_wakeup_capable(&pdev->dev, true);
>  
>  	/* Perform initial detection */
> +	info->initial_det = true;

What is protecting this from changing right after you test for it?

thanks,

greg k-h