linux-kernel - [PATCH v4 2/2] usb: dwc3: gadget: Simplify TRB reclaim logic by removing redundant 'chain' argument

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Message-ID: <20250629090414.294308-2-johannes.schneider@leica-geosystems.com>
Date: Sun, 29 Jun 2025 11:04:14 +0200
From: Johannes Schneider <johannes.schneider@...ca-geosystems.com>
To: Thinh.Nguyen@...opsys.com,
	gregkh@...uxfoundation.org
Cc: kernel@...gutronix.de,
	linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	bsp-development.geo@...ca-geosystems.com,
	Johannes Schneider <johannes.schneider@...ca-geosystems.com>
Subject: [PATCH v4 2/2] usb: dwc3: gadget: Simplify TRB reclaim logic by removing redundant 'chain' argument

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.

Acked-by: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Signed-off-by: Johannes Schneider <johannes.schneider@...ca-geosystems.com>
---
Changes in v4:
- None, patch content is the same
- re-assembled into a patch-series, and re-submission to solve b4 troubles
- Link to v3:
  1. https://lore.kernel.org/all/AM8PR06MB7521A29A8863C838B54987B6BC7BA@AM8PR06MB7521.eurprd06.prod.outlook.com/
  2. https://lore.kernel.org/all/AM8PR06MB752168CCAF31023017025DD5BC7BA@AM8PR06MB7521.eurprd06.prod.outlook.com/

Changes in v3:
- re-submission as singular patch
- Link to v2: https://lore.kernel.org/r/20250624-dwc3-fix-gadget-mtp-v2-0-0e2d9979328f@leica-geosystems.com

Changes in v2:
- None, resubmission as separate patches
- dropped Patch 3, as it did change the logic
- CC to stable
- Link to v1: https://lore.kernel.org/r/20250621-dwc3-fix-gadget-mtp-v1-0-a45e6def71bb@leica-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 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;
 	}
-- 
2.34.1