linux-kernel - Re: [PATCH v3] usb: dwc2: drd: fix soft connect when gadget is unconfigured

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Date:   Fri, 11 Mar 2022 06:12:38 +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 v3] usb: dwc2: drd: fix soft connect when gadget is
 unconfigured

On 2/16/2022 12:12 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 <hminas@...opsys.com>

> ---
> Changes in v3:
> - remove extra () in dwc2_is_device_enabled() macro.
> Changes in v2:
> - Fix build error: 'struct dwc2_hsotg' has no member named 'enabled';
>    as reported by the kernel test robot.
>    https://urldefense.com/v3/__https://lore.kernel.org/all/202202112236.AwoOTtHO-lkp@intel.com/__;!!A4F2R9G_pg!KxYqv4z1NDZM9yu_eZO1eEo1ZARNbT10DdREGmrUOJvH3Jh9soyw9Hd5lckEWwA$
>    Add dwc2_is_device_enabled() macro to handle this.
> ---
>   drivers/usb/dwc2/core.h | 2 ++
>   drivers/usb/dwc2/drd.c  | 6 ++++--
>   2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
> index 8a63da3..88c337b 100644
> --- a/drivers/usb/dwc2/core.h
> +++ b/drivers/usb/dwc2/core.h
> @@ -1418,6 +1418,7 @@ void dwc2_hsotg_core_connect(struct dwc2_hsotg *hsotg);
>   void dwc2_hsotg_disconnect(struct dwc2_hsotg *dwc2);
>   int dwc2_hsotg_set_test_mode(struct dwc2_hsotg *hsotg, int testmode);
>   #define dwc2_is_device_connected(hsotg) (hsotg->connected)
> +#define dwc2_is_device_enabled(hsotg) (hsotg->enabled)
>   int dwc2_backup_device_registers(struct dwc2_hsotg *hsotg);
>   int dwc2_restore_device_registers(struct dwc2_hsotg *hsotg, int remote_wakeup);
>   int dwc2_gadget_enter_hibernation(struct dwc2_hsotg *hsotg);
> @@ -1454,6 +1455,7 @@ static inline int dwc2_hsotg_set_test_mode(struct dwc2_hsotg *hsotg,
>   					   int testmode)
>   { return 0; }
>   #define dwc2_is_device_connected(hsotg) (0)
> +#define dwc2_is_device_enabled(hsotg) (0)
>   static inline int dwc2_backup_device_registers(struct dwc2_hsotg *hsotg)
>   { return 0; }
>   static inline int dwc2_restore_device_registers(struct dwc2_hsotg *hsotg,
> diff --git a/drivers/usb/dwc2/drd.c b/drivers/usb/dwc2/drd.c
> index 1b39c47..d8d6493 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 (dwc2_is_device_enabled(hsotg)) {
> +			/* This clear DCTL.SFTDISCON bit */
> +			dwc2_hsotg_core_connect(hsotg);
> +		}
>   	} else {
>   		if (dwc2_is_device_mode(hsotg)) {
>   			if (!dwc2_ovr_bvalid(hsotg, false))