linux-kernel - Re: [PATCH 2/3] usb: dwc3: gadget: Simplify TRB reclaim logic by removing redundant 'chain' argument

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Message-ID: <20250623224340.oszkgwnhcjhnibaz@synopsys.com>
Date: Mon, 23 Jun 2025 22:43:45 +0000
From: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To: Johannes Schneider <johannes.schneider@...ca-geosystems.com>
CC: Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        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>,
        "bsp-development.geo@...ca-geosystems.com" <bsp-development.geo@...ca-geosystems.com>
Subject: Re: [PATCH 2/3] usb: dwc3: gadget: Simplify TRB reclaim logic by
 removing redundant 'chain' argument

On Sat, Jun 21, 2025, Johannes Schneider wrote:
> 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>
> ---
>  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 99fbd29d8f46d30df558ceb23d2afe7187b4244c..a4a2bf273f943fa112f49979297023a732e0af2e 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;
>  	}
> 
> -- 
> 2.34.1
> 

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

Note: if you want the fix [Patch 1/3] to be picked up early, then it needs to
be separated from this series. Otherwise this series won't be picked up
until the next rc1 release.

Thanks,
Thinh