Re: [PATCH v2 2/3] usb: dwc3: gadget: Add support for snps,reserved-endpoints property

Thinh Nguyen
2025-02-13T01:17:53Z

On Wed, Feb 12, 2025, Andy Shevchenko wrote:
> On Wed, Feb 12, 2025 at 12:36:04PM +0200, Andy Shevchenko wrote:
> > On Wed, Feb 12, 2025 at 01:10:17AM +0000, Thinh Nguyen wrote:
> > > On Mon, Feb 03, 2025, Andy Shevchenko wrote:
>
> ...
>
> > > > static bool dwc3_gadget_endpoint_trbs_complete(struct dwc3_ep *dep,
> >
> > > > for (i = 0; i < DWC3_ENDPOINTS_NUM; i++) {
> > > > dep = dwc->eps[i];
> > > > + if (!dep)
> > > > + continue;
> > >
> > > It should be fine to ignore this check here. Something must be really
> > > wrong if there's an interrupt pointing to an endpoint that we shouldn't
> > > be touching. If we do add a check, we should print a warn or something
> > > here. But that should be a patch separate from this.
> >
> > Theoretically everything is possible as it may be HW integration bug,
> > for example. But are you asking about separate patch even from the rest
> > of the checks? Please, elaborate what do you want to see.
>
> Re-reading the code again, I don't understand. If we get to this loop
> ever (theoretically it might be an old IP with the reserved endpoints),
> we crash the kernel on the first gap in the array. And since the function
> is called on an endpoint, it doesn't mean that all endpoints are allocated,
> so I do not see the justification to issue a warning here.
> Or do you imply that DWC3_VER_IS_PRIOR(DWC3, 183A) may not have an HW
> integration similar to what we have on Intel Merrifield?
>
> For now I'm going to leave this check as is.

Oops, you are correct. I read this as the same logic as below.

>
> ...
>
> > > > static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
> >
> > > > dep = dwc->eps[epnum];
> > > > + if (!dep)
> > > > + return;
> > >
> > > Same here.
>
> Here I agree and I will add a warning message. Indeed, if we get and interrupt
> for undefined endpoint, something is not correct.
>

BR,
Thinh