linux-kernel - Re: [PATCH v7] usb: common: usb-conn-gpio: Set last role to unknown before initial detection

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Message-ID: <ZIhOm5LKwn+YVGzT@kuha.fi.intel.com>
Date:   Tue, 13 Jun 2023 14:10:19 +0300
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Prashanth K <quic_prashk@...cinc.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7] usb: common: usb-conn-gpio: Set last role to unknown
 before initial detection

Hi,

On Wed, May 31, 2023 at 08:11:14PM +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, added a new constant in enum usb_role, last_role
> is set to USB_ROLE_UNKNOWN before performing initial detection.

So why can't you fix this by just always setting the role
unconditionally to USB_ROLE_NONE in your probe function before the
initial detection?

> While at it, also handle default case for the usb_role switch
> in cdns3, intel-xhci-usb-role-switch & musb/jz4740 to avoid
> build warnings.
> 
> Fixes: 4602f3bff266 ("usb: common: add USB GPIO based connection detection driver")
> Signed-off-by: Prashanth K <quic_prashk@...cinc.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> ---
> v7: Added default case in musb/jz4740.c & intel-xhci-usb-role-switch.c to
>     avoid build warnings.
> v6: Moved USB_ROLE_UNKNOWN towards the end of enum usb_role.
> v5: Update commit text to mention the changes made in cdns3 driver.
> v4: Added Reviewed-by tag.
> v3: Added a default case in drivers/usb/cdns3/core.c as pointed out by
>     the test robot.
> v2: Added USB_ROLE_UNKNWON to enum usb_role.
> 
>  drivers/usb/cdns3/core.c                       | 2 ++
>  drivers/usb/common/usb-conn-gpio.c             | 3 +++
>  drivers/usb/musb/jz4740.c                      | 2 ++
>  drivers/usb/roles/intel-xhci-usb-role-switch.c | 2 ++
>  include/linux/usb/role.h                       | 1 +
>  5 files changed, 10 insertions(+)
> 
> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
> index dbcdf3b..69d2921 100644
> --- a/drivers/usb/cdns3/core.c
> +++ b/drivers/usb/cdns3/core.c
> @@ -252,6 +252,8 @@ static enum usb_role cdns_hw_role_state_machine(struct cdns *cdns)
>  		if (!vbus)
>  			role = USB_ROLE_NONE;
>  		break;
> +	default:
> +		break;
>  	}
>  
>  	dev_dbg(cdns->dev, "role %d -> %d\n", cdns->role, role);
> diff --git a/drivers/usb/common/usb-conn-gpio.c b/drivers/usb/common/usb-conn-gpio.c
> index e20874c..30bdb81 100644
> --- a/drivers/usb/common/usb-conn-gpio.c
> +++ b/drivers/usb/common/usb-conn-gpio.c
> @@ -257,6 +257,9 @@ 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);
>  
> diff --git a/drivers/usb/musb/jz4740.c b/drivers/usb/musb/jz4740.c
> index 5aabdd7..6d880c4 100644
> --- a/drivers/usb/musb/jz4740.c
> +++ b/drivers/usb/musb/jz4740.c
> @@ -95,6 +95,8 @@ static int jz4740_musb_role_switch_set(struct usb_role_switch *sw,
>  	case USB_ROLE_HOST:
>  		atomic_notifier_call_chain(&phy->notifier, USB_EVENT_ID, phy);
>  		break;
> +	default:
> +		break;
>  	}
>  
>  	return 0;
> diff --git a/drivers/usb/roles/intel-xhci-usb-role-switch.c b/drivers/usb/roles/intel-xhci-usb-role-switch.c
> index 5c96e92..4d6a3dd 100644
> --- a/drivers/usb/roles/intel-xhci-usb-role-switch.c
> +++ b/drivers/usb/roles/intel-xhci-usb-role-switch.c
> @@ -97,6 +97,8 @@ static int intel_xhci_usb_set_role(struct usb_role_switch *sw,
>  		val |= SW_VBUS_VALID;
>  		drd_config = DRD_CONFIG_STATIC_DEVICE;
>  		break;
> +	default:
> +		break;
>  	}
>  	val |= SW_IDPIN_EN;
>  	if (data->enable_sw_switch) {
> diff --git a/include/linux/usb/role.h b/include/linux/usb/role.h
> index b5deafd..65e790a 100644
> --- a/include/linux/usb/role.h
> +++ b/include/linux/usb/role.h
> @@ -11,6 +11,7 @@ enum usb_role {
>  	USB_ROLE_NONE,
>  	USB_ROLE_HOST,
>  	USB_ROLE_DEVICE,
> +	USB_ROLE_UNKNOWN,
>  };
>  
>  typedef int (*usb_role_switch_set_t)(struct usb_role_switch *sw,
> -- 
> 2.7.4

-- 
heikki