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

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Message-ID:
 <AM8PR06MB7521915A5FB0DDD1DA38BA3ABC47A@AM8PR06MB7521.eurprd06.prod.outlook.com>
Date: Sun, 29 Jun 2025 08:45:45 +0000
From: SCHNEIDER Johannes <johannes.schneider@...ca-geosystems.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC: Thinh Nguyen <Thinh.Nguyen@...opsys.com>, Pengutronix Kernel Team
	<kernel@...gutronix.de>, "linux-usb@...r.kernel.org"
	<linux-usb@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, GEO-CHHER-bsp-development
	<bsp-development.geo@...ca-geosystems.com>
Subject: Re: [PATCH v3] usb: dwc3: gadget: Simplify TRB reclaim logic by
 removing redundant 'chain' argument

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@...ca-geosystems.com>
> > Acked-by: Thinh Nguyen <Thinh.Nguyen@...opsys.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


Thanks for the patience
Gruß
Johannes