[PATCH v2 0/2] usb: dwc3: gadget: Fix isoc interrupt check

[PATCH v2 0/2] usb: dwc3: gadget: Fix isoc interrupt check

[Thinh Nguyen]

Fix issues where usb_request->no_interrupt is set for isoc transfers.
* Make sure no interrupt is asserted if no_interrupt is set
* Make sure to stop reclaiming TRBs when the driver needs to stop


Thinh Nguyen (2):
  usb: dwc3: gadget: Stop processing more requests on IMI
  usb: dwc3: gadget: Don't set IMI for no_interrupt

 drivers/usb/dwc3/gadget.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

Changes in v2:
* Fix missing cover letter subject
* No need to check for the last chained TRB


base-commit: fb8f60dd1b67520e0e0d7978ef17d015690acfc1
-- 
2.28.0

[PATCH v2 1/2] usb: dwc3: gadget: Stop processing more requests on IMI

[Thinh Nguyen]

When servicing a transfer completion event, the dwc3 driver will reclaim
TRBs of started requests up to the request associated with the interrupt
event. Currently we don't check for interrupt due to missed isoc, and
the driver may attempt to reclaim TRBs beyond the associated event. This
causes invalid memory access when the hardware still owns the TRB. If
there's a missed isoc TRB with IMI (interrupt on missed isoc), make sure
to stop servicing further.

Note that only the last TRB of chained TRBs has its status updated with
missed isoc.

Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
Cc: stable@vger.kernel.org
Reported-by: Jeff Vanhoof <jdv1029@gmail.com>
Reported-by: Dan Vacura <w36195@motorola.com>
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
---
 Changes in v2:
 - No need to check for CHN=0 since only the last TRB has its status
   updated to missed isoc

 drivers/usb/dwc3/gadget.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index dd8ecbe61bec..230b3c660054 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -3248,6 +3248,10 @@ static int dwc3_gadget_ep_reclaim_completed_trb(struct dwc3_ep *dep,
 	if (event->status & DEPEVT_STATUS_SHORT && !chain)
 		return 1;
 
+	if ((trb->ctrl & DWC3_TRB_CTRL_ISP_IMI) &&
+	    DWC3_TRB_SIZE_TRBSTS(trb->size) == DWC3_TRBSTS_MISSED_ISOC)
+		return 1;
+
 	if ((trb->ctrl & DWC3_TRB_CTRL_IOC) ||
 	    (trb->ctrl & DWC3_TRB_CTRL_LST))
 		return 1;
-- 
2.28.0

Re: [PATCH v2 1/2] usb: dwc3: gadget: Stop processing more requests on IMI

[Jeff Vanhoof]

On Mon, Oct 24, 2022 at 06:27:57PM -0700, Thinh Nguyen wrote:
> When servicing a transfer completion event, the dwc3 driver will reclaim
> TRBs of started requests up to the request associated with the interrupt
> event. Currently we don't check for interrupt due to missed isoc, and
> the driver may attempt to reclaim TRBs beyond the associated event. This
> causes invalid memory access when the hardware still owns the TRB. If
> there's a missed isoc TRB with IMI (interrupt on missed isoc), make sure
> to stop servicing further.
> 
> Note that only the last TRB of chained TRBs has its status updated with
> missed isoc.
> 
> Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
> Cc: stable@vger.kernel.org
> Reported-by: Jeff Vanhoof <jdv1029@gmail.com>
> Reported-by: Dan Vacura <w36195@motorola.com>
> Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
> ---
>  Changes in v2:
>  - No need to check for CHN=0 since only the last TRB has its status
>    updated to missed isoc
> 
>  drivers/usb/dwc3/gadget.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index dd8ecbe61bec..230b3c660054 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -3248,6 +3248,10 @@ static int dwc3_gadget_ep_reclaim_completed_trb(struct dwc3_ep *dep,
>  	if (event->status & DEPEVT_STATUS_SHORT && !chain)
>  		return 1;
>  
> +	if ((trb->ctrl & DWC3_TRB_CTRL_ISP_IMI) &&
> +	    DWC3_TRB_SIZE_TRBSTS(trb->size) == DWC3_TRBSTS_MISSED_ISOC)
> +		return 1;
> +
>  	if ((trb->ctrl & DWC3_TRB_CTRL_IOC) ||
>  	    (trb->ctrl & DWC3_TRB_CTRL_LST))
>  		return 1;
> -- 
> 2.28.0
>

Testing shows that the changes appear to work to prevent the arm-smmu panic I
was seeing after missed isoc errors. Also, changes to reclaim trbs only up to
the associated interrupt event make sense.

Reviewed-by: Jeff Vanhoof <jdv1029@gmail.com>
Tested-by: Jeff Vanhoof <jdv1029@gmail.com>

Regards,
Jeff
 

Re: [PATCH v2 1/2] usb: dwc3: gadget: Stop processing more requests on IMI

[Jeff Vanhoof]

Hi Thinh,

On Mon, Oct 24, 2022 at 11:45:48PM -0500, Jeff Vanhoof wrote:
> On Mon, Oct 24, 2022 at 06:27:57PM -0700, Thinh Nguyen wrote:
> > When servicing a transfer completion event, the dwc3 driver will reclaim
> > TRBs of started requests up to the request associated with the interrupt
> > event. Currently we don't check for interrupt due to missed isoc, and
> > the driver may attempt to reclaim TRBs beyond the associated event. This
> > causes invalid memory access when the hardware still owns the TRB. If
> > there's a missed isoc TRB with IMI (interrupt on missed isoc), make sure
> > to stop servicing further.
> > 
> > Note that only the last TRB of chained TRBs has its status updated with
> > missed isoc.
> > 
> > Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
> > Cc: stable@vger.kernel.org
> > Reported-by: Jeff Vanhoof <jdv1029@gmail.com>
> > Reported-by: Dan Vacura <w36195@motorola.com>
> > Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
> > ---
> >  Changes in v2:
> >  - No need to check for CHN=0 since only the last TRB has its status
> >    updated to missed isoc
> > 
> >  drivers/usb/dwc3/gadget.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> > index dd8ecbe61bec..230b3c660054 100644
> > --- a/drivers/usb/dwc3/gadget.c
> > +++ b/drivers/usb/dwc3/gadget.c
> > @@ -3248,6 +3248,10 @@ static int dwc3_gadget_ep_reclaim_completed_trb(struct dwc3_ep *dep,
> >  	if (event->status & DEPEVT_STATUS_SHORT && !chain)
> >  		return 1;
> >  
> > +	if ((trb->ctrl & DWC3_TRB_CTRL_ISP_IMI) &&
> > +	    DWC3_TRB_SIZE_TRBSTS(trb->size) == DWC3_TRBSTS_MISSED_ISOC)
> > +		return 1;
> > +
> >  	if ((trb->ctrl & DWC3_TRB_CTRL_IOC) ||
> >  	    (trb->ctrl & DWC3_TRB_CTRL_LST))
> >  		return 1;
> > -- 
> > 2.28.0
> >
> 
> Testing shows that the changes appear to work to prevent the arm-smmu panic I
> was seeing after missed isoc errors. Also, changes to reclaim trbs only up to
> the associated interrupt event make sense.
> 
> Reviewed-by: Jeff Vanhoof <jdv1029@gmail.com>
> Tested-by: Jeff Vanhoof <jdv1029@gmail.com>
> 
> Regards,
> Jeff
> 

I just followed up with Dan and he mentioned that he was still seeing the arm-smmu panic on his baseline. I will work with him this afternoon to better understand what may be going on there. Let's hold off on merging these changes in until we figure out what is going on. He and I are testing off of different baselines (5.10 vs 5.15), different USB speeds (USB 3 vs 2), and are using different hardware, so I don't know yet why we are seeing a difference here.

Regards,
Jeff

Re: [PATCH v2 1/2] usb: dwc3: gadget: Stop processing more requests on IMI

[Jeff Vanhoof]

Hi Thinh,

On Tue, Oct 25, 2022 at 11:42:37AM -0500, Jeff Vanhoof wrote:
> Hi Thinh,
> 
> On Mon, Oct 24, 2022 at 11:45:48PM -0500, Jeff Vanhoof wrote:
> > On Mon, Oct 24, 2022 at 06:27:57PM -0700, Thinh Nguyen wrote:
> > > When servicing a transfer completion event, the dwc3 driver will reclaim
> > > TRBs of started requests up to the request associated with the interrupt
> > > event. Currently we don't check for interrupt due to missed isoc, and
> > > the driver may attempt to reclaim TRBs beyond the associated event. This
> > > causes invalid memory access when the hardware still owns the TRB. If
> > > there's a missed isoc TRB with IMI (interrupt on missed isoc), make sure
> > > to stop servicing further.
> > > 
> > > Note that only the last TRB of chained TRBs has its status updated with
> > > missed isoc.
> > > 
> > > Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
> > > Cc: stable@vger.kernel.org
> > > Reported-by: Jeff Vanhoof <jdv1029@gmail.com>
> > > Reported-by: Dan Vacura <w36195@motorola.com>
> > > Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
> > > ---
> > >  Changes in v2:
> > >  - No need to check for CHN=0 since only the last TRB has its status
> > >    updated to missed isoc
> > > 
> > >  drivers/usb/dwc3/gadget.c | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > > 
> > > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> > > index dd8ecbe61bec..230b3c660054 100644
> > > --- a/drivers/usb/dwc3/gadget.c
> > > +++ b/drivers/usb/dwc3/gadget.c
> > > @@ -3248,6 +3248,10 @@ static int dwc3_gadget_ep_reclaim_completed_trb(struct dwc3_ep *dep,
> > >  	if (event->status & DEPEVT_STATUS_SHORT && !chain)
> > >  		return 1;
> > >  
> > > +	if ((trb->ctrl & DWC3_TRB_CTRL_ISP_IMI) &&
> > > +	    DWC3_TRB_SIZE_TRBSTS(trb->size) == DWC3_TRBSTS_MISSED_ISOC)
> > > +		return 1;
> > > +
> > >  	if ((trb->ctrl & DWC3_TRB_CTRL_IOC) ||
> > >  	    (trb->ctrl & DWC3_TRB_CTRL_LST))
> > >  		return 1;
> > > -- 
> > > 2.28.0
> > >
> > 
> > Testing shows that the changes appear to work to prevent the arm-smmu panic I
> > was seeing after missed isoc errors. Also, changes to reclaim trbs only up to
> > the associated interrupt event make sense.
> > 
> > Reviewed-by: Jeff Vanhoof <jdv1029@gmail.com>
> > Tested-by: Jeff Vanhoof <jdv1029@gmail.com>
> > 
> > Regards,
> > Jeff
> > 
> 
> I just followed up with Dan and he mentioned that he was still seeing the arm-smmu panic on his baseline. I will work with him this afternoon to better understand what may be going on there. Let's hold off on merging these changes in until we figure out what is going on. He and I are testing off of different baselines (5.10 vs 5.15), different USB speeds (USB 3 vs 2), and are using different hardware, so I don't know yet why we are seeing a difference here.
> 
> Regards,
> Jeff
> 

Between the changes for PATCH v2 1/2 & PATCH v2 2/2, are there any extra
precautions required for when scatter gather is in use? Should the IMI bit be
set only for the last item in the sg list? I suspect something in this area but
I have no proof yet. Your thoughts?

Thanks,
Jeff

[PATCH v2 2/2] usb: dwc3: gadget: Don't set IMI for no_interrupt

[Thinh Nguyen]

The gadget driver may have a certain expectation of how the request
completion flow should be from to its configuration. Make sure the
controller driver respect that. That is, don't set IMI (Interrupt on
Missed Isoc) when usb_request->no_interrupt is set.

Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
Cc: stable@vger.kernel.org
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
---
 Changes in v2:
 - None

 drivers/usb/dwc3/gadget.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 230b3c660054..702bdf42ad2f 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1292,8 +1292,8 @@ static void dwc3_prepare_one_trb(struct dwc3_ep *dep,
 			trb->ctrl = DWC3_TRBCTL_ISOCHRONOUS;
 		}
 
-		/* always enable Interrupt on Missed ISOC */
-		trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
+		if (!req->request.no_interrupt)
+			trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
 		break;
 
 	case USB_ENDPOINT_XFER_BULK:
-- 
2.28.0

Re: [PATCH v2 2/2] usb: dwc3: gadget: Don't set IMI for no_interrupt

[Jeff Vanhoof]

On Mon, Oct 24, 2022 at 06:28:04PM -0700, Thinh Nguyen wrote:
> The gadget driver may have a certain expectation of how the request
> completion flow should be from to its configuration. Make sure the
> controller driver respect that. That is, don't set IMI (Interrupt on
> Missed Isoc) when usb_request->no_interrupt is set.
> 
> Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
> Cc: stable@vger.kernel.org
> Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
> ---
>  Changes in v2:
>  - None
> 
>  drivers/usb/dwc3/gadget.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 230b3c660054..702bdf42ad2f 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1292,8 +1292,8 @@ static void dwc3_prepare_one_trb(struct dwc3_ep *dep,
>  			trb->ctrl = DWC3_TRBCTL_ISOCHRONOUS;
>  		}
>  
> -		/* always enable Interrupt on Missed ISOC */
> -		trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
> +		if (!req->request.no_interrupt)
> +			trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
>  		break;
>  
>  	case USB_ENDPOINT_XFER_BULK:
> -- 
> 2.28.0
>

No new issue seen during testing. Described changes make sense to do.

Reviewed-by: Jeff Vanhoof <jdv1029@gmail.com>
Tested-by: Jeff Vanhoof <jdv1029@gmail.com>

Regards,
Jeff

Re: [PATCH v2 2/2] usb: dwc3: gadget: Don't set IMI for no_interrupt

[Jeff Vanhoof]

Hi Thinh,

On Mon, Oct 24, 2022 at 11:51:50PM -0500, Jeff Vanhoof wrote:
> On Mon, Oct 24, 2022 at 06:28:04PM -0700, Thinh Nguyen wrote:
> > The gadget driver may have a certain expectation of how the request
> > completion flow should be from to its configuration. Make sure the
> > controller driver respect that. That is, don't set IMI (Interrupt on
> > Missed Isoc) when usb_request->no_interrupt is set.
> > 
> > Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
> > ---
> >  Changes in v2:
> >  - None
> > 
> >  drivers/usb/dwc3/gadget.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> > index 230b3c660054..702bdf42ad2f 100644
> > --- a/drivers/usb/dwc3/gadget.c
> > +++ b/drivers/usb/dwc3/gadget.c
> > @@ -1292,8 +1292,8 @@ static void dwc3_prepare_one_trb(struct dwc3_ep *dep,
> >  			trb->ctrl = DWC3_TRBCTL_ISOCHRONOUS;
> >  		}
> >  
> > -		/* always enable Interrupt on Missed ISOC */
> > -		trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
> > +		if (!req->request.no_interrupt)
> > +			trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
> >  		break;
> >  
> >  	case USB_ENDPOINT_XFER_BULK:
> > -- 
> > 2.28.0
> >
> 
<snip>

For scatter gather, shouldn't the IMI bit be set only for the TRB associated
to the last item in the sg list?  Do we need to do something similar to what
that was done for IOC in this area?

For ex.:
+	if ((!req->request.no_interrupt && !chain) || must_interrupt)
+		trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;

BTW, Dan indicated that this seems to help resolve the crash mentioned in
[PATCH v2 1/2] of this chain.

Thanks,
Jeff

Re: [PATCH v2 2/2] usb: dwc3: gadget: Don't set IMI for no_interrupt

[Thinh Nguyen]

On Tue, Oct 25, 2022, Jeff Vanhoof wrote:
> Hi Thinh,
> 
> On Mon, Oct 24, 2022 at 11:51:50PM -0500, Jeff Vanhoof wrote:
> > On Mon, Oct 24, 2022 at 06:28:04PM -0700, Thinh Nguyen wrote:
> > > The gadget driver may have a certain expectation of how the request
> > > completion flow should be from to its configuration. Make sure the
> > > controller driver respect that. That is, don't set IMI (Interrupt on
> > > Missed Isoc) when usb_request->no_interrupt is set.
> > > 
> > > Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
> > > Cc: stable@vger.kernel.org
> > > Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
> > > ---
> > >  Changes in v2:
> > >  - None
> > > 
> > >  drivers/usb/dwc3/gadget.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> > > index 230b3c660054..702bdf42ad2f 100644
> > > --- a/drivers/usb/dwc3/gadget.c
> > > +++ b/drivers/usb/dwc3/gadget.c
> > > @@ -1292,8 +1292,8 @@ static void dwc3_prepare_one_trb(struct dwc3_ep *dep,
> > >  			trb->ctrl = DWC3_TRBCTL_ISOCHRONOUS;
> > >  		}
> > >  
> > > -		/* always enable Interrupt on Missed ISOC */
> > > -		trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
> > > +		if (!req->request.no_interrupt)
> > > +			trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
> > >  		break;
> > >  
> > >  	case USB_ENDPOINT_XFER_BULK:
> > > -- 
> > > 2.28.0
> > >
> > 
> <snip>
> 
> For scatter gather, shouldn't the IMI bit be set only for the TRB associated
> to the last item in the sg list?  Do we need to do something similar to what
> that was done for IOC in this area?
> 
> For ex.:
> +	if ((!req->request.no_interrupt && !chain) || must_interrupt)
> +		trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
> 
> BTW, Dan indicated that this seems to help resolve the crash mentioned in
> [PATCH v2 1/2] of this chain.
> 

Actually, that's correct. Just ignore the "must_interrupt" setting. The
programming guide actually noted to set the IMI for the last TRB of the
chain also.

I'll send a fix to this.

Thanks,
Thinh

Re: [PATCH v2 2/2] usb: dwc3: gadget: Don't set IMI for no_interrupt

[Thinh Nguyen]

On Tue, Oct 25, 2022, Thinh Nguyen wrote:
> On Tue, Oct 25, 2022, Jeff Vanhoof wrote:
> > Hi Thinh,
> > 
> > On Mon, Oct 24, 2022 at 11:51:50PM -0500, Jeff Vanhoof wrote:
> > > On Mon, Oct 24, 2022 at 06:28:04PM -0700, Thinh Nguyen wrote:
> > > > The gadget driver may have a certain expectation of how the request
> > > > completion flow should be from to its configuration. Make sure the
> > > > controller driver respect that. That is, don't set IMI (Interrupt on
> > > > Missed Isoc) when usb_request->no_interrupt is set.
> > > > 
> > > > Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
> > > > Cc: stable@vger.kernel.org
> > > > Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
> > > > ---
> > > >  Changes in v2:
> > > >  - None
> > > > 
> > > >  drivers/usb/dwc3/gadget.c | 4 ++--
> > > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> > > > index 230b3c660054..702bdf42ad2f 100644
> > > > --- a/drivers/usb/dwc3/gadget.c
> > > > +++ b/drivers/usb/dwc3/gadget.c
> > > > @@ -1292,8 +1292,8 @@ static void dwc3_prepare_one_trb(struct dwc3_ep *dep,
> > > >  			trb->ctrl = DWC3_TRBCTL_ISOCHRONOUS;
> > > >  		}
> > > >  
> > > > -		/* always enable Interrupt on Missed ISOC */
> > > > -		trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
> > > > +		if (!req->request.no_interrupt)
> > > > +			trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
> > > >  		break;
> > > >  
> > > >  	case USB_ENDPOINT_XFER_BULK:
> > > > -- 
> > > > 2.28.0
> > > >
> > > 
> > <snip>
> > 
> > For scatter gather, shouldn't the IMI bit be set only for the TRB associated
> > to the last item in the sg list?  Do we need to do something similar to what
> > that was done for IOC in this area?
> > 
> > For ex.:
> > +	if ((!req->request.no_interrupt && !chain) || must_interrupt)
> > +		trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
> > 
> > BTW, Dan indicated that this seems to help resolve the crash mentioned in
> > [PATCH v2 1/2] of this chain.
> > 
> 
> Actually, that's correct. Just ignore the "must_interrupt" setting. The
> programming guide actually noted to set the IMI for the last TRB of the
> chain also.
> 
> I'll send a fix to this.
> 

Hm... I wonder if it's still better to ignore no_interrupt and
immediately notify the gadget driver of missed isoc. It's redundant to
have both IOC and IMI set under the same condition, but I guess it
doesn't hurt to set it for clarity.

So it's either
	if (!no_interrupt && !chain)
		trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
or
	if (!chain)
		trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;

Either way, this needs a fix.

Thanks,
Thinh