Re: [RFC] usb: dwc3: core: Fix RAM interface getting stuck during enumeration

[Krishna Kurapati PSSNV]

On 10/13/2023 12:55 AM, Wesley Cheng wrote:
> Hi Krishna,
>
> On 10/11/2023 3:02 AM, Krishna Kurapati wrote:
> > This implementation is to fix RAM interface getting stuck during

> > Synopsys confirmed that the issue is present on all USB3 devices and
> > as a workaround, suggested to re-initialize device mode.
> >
> > Signed-off-by: Krishna Kurapati <quic_kriskura@xxxxxxxxxxx>
> > ---
> >   drivers/usb/dwc3/core.c   | 20 ++++++++++++++++++++
> >   drivers/usb/dwc3/core.h   |  4 ++++
> >   drivers/usb/dwc3/drd.c    |  5 +++++
> >   drivers/usb/dwc3/gadget.c |  6 ++++--
> >   4 files changed, 33 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > index 44ee8526dc28..d18b81cccdc5 100644
> > --- a/drivers/usb/dwc3/core.c
> > +++ b/drivers/usb/dwc3/core.c
> > @@ -122,6 +122,7 @@ static void __dwc3_set_mode(struct work_struct *work)
> >       unsigned long flags;
> >       int ret;
> >       u32 reg;
> > +    u8 timeout = 100;
> >       u32 desired_dr_role;
> >       mutex_lock(&dwc->mutex);
> > @@ -137,6 +138,25 @@ static void __dwc3_set_mode(struct work_struct 
> > *work)
> >       if (!desired_dr_role)
> >           goto out;
> > +    /*
> > +     * STAR 5001544 - If cable disconnect doesn't generate
> > +     * disconnect event in device mode, then re-initialize the
> > +     * controller.
> > +     */
> > +    if ((dwc->cable_disconnected == true) &&
> > +        (dwc->current_dr_role == DWC3_GCTL_PRTCAP_DEVICE)) {
> > +        while (dwc->connected == true && timeout != 0) {
> > +            mdelay(10);
> > +            timeout--;
> > +        }
> > +
> > +        if (timeout == 0) {
> > +            dwc3_gadget_soft_disconnect(dwc);
> > +            udelay(100);
> > +            dwc3_gadget_soft_connect(dwc);
> > +        }
> > +    }
> > +
> >       if (desired_dr_role == dwc->current_dr_role)
> >           goto out;
> > diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> > index c6c87acbd376..7642330cf608 100644
> > --- a/drivers/usb/dwc3/core.h
> > +++ b/drivers/usb/dwc3/core.h
> > @@ -1355,6 +1355,7 @@ struct dwc3 {
> >       int            last_fifo_depth;
> >       int            num_ep_resized;
> >       struct dentry        *debug_root;
> > +    bool            cable_disconnected;
> >   };
> >   #define INCRX_BURST_MODE 0
> > @@ -1568,6 +1569,9 @@ void dwc3_event_buffers_cleanup(struct dwc3 *dwc);
> >   int dwc3_core_soft_reset(struct dwc3 *dwc);
> > +int dwc3_gadget_soft_disconnect(struct dwc3 *dwc);
> > +int dwc3_gadget_soft_connect(struct dwc3 *dwc);
> > +
> >   #if IS_ENABLED(CONFIG_USB_DWC3_HOST) || 
> > IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
> >   int dwc3_host_init(struct dwc3 *dwc);
> >   void dwc3_host_exit(struct dwc3 *dwc);
> > diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
> > index 039bf241769a..593c023fc39a 100644
> > --- a/drivers/usb/dwc3/drd.c
> > +++ b/drivers/usb/dwc3/drd.c
> > @@ -446,6 +446,8 @@ static int dwc3_usb_role_switch_set(struct 
> > usb_role_switch *sw,
> >       struct dwc3 *dwc = usb_role_switch_get_drvdata(sw);
> >       u32 mode;
> > +    dwc->cable_disconnected = false;
> > +
> >       switch (role) {
> >       case USB_ROLE_HOST:
> >           mode = DWC3_GCTL_PRTCAP_HOST;
> > @@ -454,6 +456,9 @@ static int dwc3_usb_role_switch_set(struct 
> > usb_role_switch *sw,
> >           mode = DWC3_GCTL_PRTCAP_DEVICE;
> >           break;
> >       default:
> > +        if (role == USB_ROLE_NONE)
> > +            dwc->cable_disconnected = true;
> > +
>
> How do we handle cases where role switch isn't used? (ie extcon or maybe 
> no cable connection notification at all)

Hi Wesley,

 Since I was considering fixing it during disconnect, I made it in role 
switch. So no cable connection notification case has been ruled out in 
this patch. But yes, extcon is a valid case. Will need to account for it.

Regards,
Krishna,