linux-kernel - Re: [PATCH] usb: dwc2: drd: fix soft connect when gadget is unconfigured

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Message-ID: <7414fa06-ebe1-4ab2-b4c6-294568e89f4c@synopsys.com>
Date:   Fri, 11 Feb 2022 08:03:51 +0000
From:   Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
To:     Fabrice Gasnier <fabrice.gasnier@...s.st.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:     "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "amelie.delaunay@...s.st.com" <amelie.delaunay@...s.st.com>,
        "alexandre.torgue@...s.st.com" <alexandre.torgue@...s.st.com>
Subject: Re: [PATCH] usb: dwc2: drd: fix soft connect when gadget is
 unconfigured

On 2/9/2022 8:15 PM, Fabrice Gasnier wrote:
> When the gadget driver hasn't been (yet) configured, and the cable is
> connected to a HOST, the SFTDISCON gets cleared unconditionally, so the
> HOST tries to enumerate it.
> At the host side, this can result in a stuck USB port or worse. When
> getting lucky, some dmesg can be observed at the host side:
>   new high-speed USB device number ...
>   device descriptor read/64, error -110
> 
> Fix it in drd, by checking the enabled flag before calling
> dwc2_hsotg_core_connect(). It will be called later, once configured,
> by the normal flow:
> - udc_bind_to_driver
>   - usb_gadget_connect
>     - dwc2_hsotg_pullup
>       - dwc2_hsotg_core_connect
> 
> Fixes: 17f934024e84 ("usb: dwc2: override PHY input signals with usb role switch support")
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@...s.st.com>

Acked-by: Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>

> ---
>   drivers/usb/dwc2/drd.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/dwc2/drd.c b/drivers/usb/dwc2/drd.c
> index 1b39c47..9b6d44d 100644
> --- a/drivers/usb/dwc2/drd.c
> +++ b/drivers/usb/dwc2/drd.c
> @@ -130,8 +130,10 @@ static int dwc2_drd_role_sw_set(struct usb_role_switch *sw, enum usb_role role)
>   		already = dwc2_ovr_avalid(hsotg, true);
>   	} else if (role == USB_ROLE_DEVICE) {
>   		already = dwc2_ovr_bvalid(hsotg, true);
> -		/* This clear DCTL.SFTDISCON bit */
> -		dwc2_hsotg_core_connect(hsotg);
> +		if (hsotg->enabled) {
> +			/* This clear DCTL.SFTDISCON bit */
> +			dwc2_hsotg_core_connect(hsotg);
> +		}
>   	} else {
>   		if (dwc2_is_device_mode(hsotg)) {
>   			if (!dwc2_ovr_bvalid(hsotg, false))