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

Greg Kroah-Hartman
2025-06-29T09:06:29Z

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@leica-geosystems.com>
> > > Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
> > > ---
> > > 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