Re: [PATCH v3] usb: dwc3: gadget: Simplify TRB reclaim logic by removing redundant 'chain' argument

[Greg Kroah-Hartman]

On Sun, Jun 29, 2025 at 08:45:45AM +0000, SCHNEIDER Johannes wrote:
> Hoi Greg,
> 
> 
> > > Now that the TRB reclaim logic always inspects the TRB's CHN (Chain) bit
> > > directly to determine whether a TRB is part of a chain, the explicit
> > > 'chain' parameter passed into dwc3_gadget_ep_reclaim_completed_trb()
> > > is no longer necessary.
> > >
> > > This cleanup simplifies the reclaim code by avoiding duplication of
> > > chain state tracking, and makes the reclaim logic rely entirely on the
> > > hardware descriptor flags — which are already present and accurate at
> > > this stage.
> > >
> > > No functional changes intended.
> > >
> > > Signed-off-by: Johannes Schneider <johannes.schneider@xxxxxxxxxxxxxxxxxxxx>
> > > Acked-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
> > > ---
> > > v3: no changes, re-submission as single patch
> > > v2: no changes to the patch, "faulty" re-submission
> > > v1: initial submission as part of a series
> > > Link:
> > >
> > >  drivers/usb/dwc3/gadget.c | 8 ++++----
> > >  1 file changed, 4 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> > > index 99fbd29d8f46..a4a2bf273f94 100644
> > > --- a/drivers/usb/dwc3/gadget.c
> > > +++ b/drivers/usb/dwc3/gadget.c
> > > @@ -3497,7 +3497,7 @@ static void dwc3_gadget_free_endpoints(struct dwc3 *dwc)
> > >
> > >  static int dwc3_gadget_ep_reclaim_completed_trb(struct dwc3_ep *dep,
> > >               struct dwc3_request *req, struct dwc3_trb *trb,
> > > -             const struct dwc3_event_depevt *event, int status, int chain)
> > > +             const struct dwc3_event_depevt *event, int status)
> > >  {
> > >       unsigned int            count;
> > >
> > > @@ -3549,7 +3549,8 @@ static int dwc3_gadget_ep_reclaim_completed_trb(struct dwc3_ep *dep,
> > >       if ((trb->ctrl & DWC3_TRB_CTRL_HWO) && status != -ESHUTDOWN)
> > >               return 1;
> > >
> > > -     if (event->status & DEPEVT_STATUS_SHORT && !chain)
> > > +     if (event->status & DEPEVT_STATUS_SHORT &&
> > > +         !(trb->ctrl & DWC3_TRB_CTRL_CHN))
> > >               return 1;
> > >
> > >       if ((trb->ctrl & DWC3_TRB_CTRL_ISP_IMI) &&
> > > @@ -3576,8 +3577,7 @@ static int dwc3_gadget_ep_reclaim_trb_sg(struct dwc3_ep *dep,
> > >               trb = &dep->trb_pool[dep->trb_dequeue];
> > >
> > >               ret = dwc3_gadget_ep_reclaim_completed_trb(dep, req,
> > > -                             trb, event, status,
> > > -                             !!(trb->ctrl & DWC3_TRB_CTRL_CHN));
> > > +                             trb, event, status);
> > >               if (ret)
> > >                       break;
> > >       }
> > > --
> > > 2.43.0
> > >
> > 
> > Applying just this patch I get:
> > 
> >   CC [M]  drivers/usb/dwc3/gadget.o
> > drivers/usb/dwc3/gadget.c: In function ‘dwc3_gadget_ep_reclaim_completed_trb’:
> > drivers/usb/dwc3/gadget.c:3517:13: error: ‘chain’ undeclared (first use in this function)
> >  3517 |         if (chain && (trb->ctrl & DWC3_TRB_CTRL_HWO))
> >       |             ^~~~~
> > drivers/usb/dwc3/gadget.c:3517:13: note: each undeclared identifier is reported only once for each function it appears in
> > 
> > So that's not going to work :(
> > 
> 
> Oh - sorry! i shouldn't have pulled the initial series apart :-(
> 
> I'll re-submit both patches together as v4 (this time both with cc-stable)
> ... without b4 to have a new mail tread

The first patch is already in my tree, I can't drop that, sorry.  Just
resend this one on it's own please.

thanks,

greg k-h