linux-kernel - [PATCH v2] usb: dwc3: Remove WARN_ON for device endpoint command timeouts

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Message-ID: <20250807014639.1596-1-selvarasu.g@samsung.com>
Date: Thu,  7 Aug 2025 07:16:31 +0530
From: Selvarasu Ganesan <selvarasu.g@...sung.com>
To: Thinh.Nguyen@...opsys.com, gregkh@...uxfoundation.org,
	m.grzeschik@...gutronix.de, balbi@...com, bigeasy@...utronix.de,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: jh0801.jung@...sung.com, dh10.jung@...sung.com, akash.m5@...sung.com,
	hongpooh.kim@...sung.com, eomji.oh@...sung.com, shijie.cai@...sung.com,
	alim.akhtar@...sung.com, muhammed.ali@...sung.com, thiagu.r@...sung.com,
	Selvarasu Ganesan <selvarasu.g@...sung.com>, stable@...r.kernel.org
Subject: [PATCH v2] usb: dwc3: Remove WARN_ON for device endpoint command
 timeouts

This commit addresses a rarely observed endpoint command timeout
which causes kernel panic due to warn when 'panic_on_warn' is enabled
and unnecessary call trace prints when 'panic_on_warn' is disabled.
It is seen during fast software-controlled connect/disconnect testcases.
The following is one such endpoint command timeout that we observed:

1. Connect
   =======
->dwc3_thread_interrupt
 ->dwc3_ep0_interrupt
  ->configfs_composite_setup
   ->composite_setup
    ->usb_ep_queue
     ->dwc3_gadget_ep0_queue
      ->__dwc3_gadget_ep0_queue
       ->__dwc3_ep0_do_control_data
        ->dwc3_send_gadget_ep_cmd

2. Disconnect
   ==========
->dwc3_thread_interrupt
 ->dwc3_gadget_disconnect_interrupt
  ->dwc3_ep0_reset_state
   ->dwc3_ep0_end_control_data
    ->dwc3_send_gadget_ep_cmd

In the issue scenario, in Exynos platforms, we observed that control
transfers for the previous connect have not yet been completed and end
transfer command sent as a part of the disconnect sequence and
processing of USB_ENDPOINT_HALT feature request from the host timeout.
This maybe an expected scenario since the controller is processing EP
commands sent as a part of the previous connect. It maybe better to
remove WARN_ON in all places where device endpoint commands are sent to
avoid unnecessary kernel panic due to warn.

Cc: stable@...r.kernel.org
Signed-off-by: Akash M <akash.m5@...sung.com>
Signed-off-by: Selvarasu Ganesan <selvarasu.g@...sung.com>
---

Changes in v2:
- Removed the 'Fixes' tag from the commit message, as this patch does
  not contain a fix.
- And Retained the 'stable' tag, as these changes are intended to be
  applied across all stable kernels.
- Additionally, replaced 'dev_warn*' with 'dev_err*'."
Link to v1: https://lore.kernel.org/all/20250807005638.thhsgjn73aaov2af@synopsys.com/
---
 drivers/usb/dwc3/ep0.c    | 20 ++++++++++++++++----
 drivers/usb/dwc3/gadget.c | 10 ++++++++--
 2 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
index 666ac432f52d..b4229aa13f37 100644
--- a/drivers/usb/dwc3/ep0.c
+++ b/drivers/usb/dwc3/ep0.c
@@ -288,7 +288,9 @@ void dwc3_ep0_out_start(struct dwc3 *dwc)
 	dwc3_ep0_prepare_one_trb(dep, dwc->ep0_trb_addr, 8,
 			DWC3_TRBCTL_CONTROL_SETUP, false);
 	ret = dwc3_ep0_start_trans(dep);
-	WARN_ON(ret < 0);
+	if (ret < 0)
+		dev_err(dwc->dev, "ep0 out start transfer failed: %d\n", ret);
+
 	for (i = 2; i < DWC3_ENDPOINTS_NUM; i++) {
 		struct dwc3_ep *dwc3_ep;
 
@@ -1061,7 +1063,9 @@ static void __dwc3_ep0_do_control_data(struct dwc3 *dwc,
 		ret = dwc3_ep0_start_trans(dep);
 	}
 
-	WARN_ON(ret < 0);
+	if (ret < 0)
+		dev_err(dwc->dev,
+			"ep0 data phase start transfer failed: %d\n", ret);
 }
 
 static int dwc3_ep0_start_control_status(struct dwc3_ep *dep)
@@ -1078,7 +1082,12 @@ static int dwc3_ep0_start_control_status(struct dwc3_ep *dep)
 
 static void __dwc3_ep0_do_control_status(struct dwc3 *dwc, struct dwc3_ep *dep)
 {
-	WARN_ON(dwc3_ep0_start_control_status(dep));
+	int	ret;
+
+	ret = dwc3_ep0_start_control_status(dep);
+	if (ret)
+		dev_err(dwc->dev,
+			"ep0 status phase start transfer failed: %d\n", ret);
 }
 
 static void dwc3_ep0_do_control_status(struct dwc3 *dwc,
@@ -1121,7 +1130,10 @@ void dwc3_ep0_end_control_data(struct dwc3 *dwc, struct dwc3_ep *dep)
 	cmd |= DWC3_DEPCMD_PARAM(dep->resource_index);
 	memset(&params, 0, sizeof(params));
 	ret = dwc3_send_gadget_ep_cmd(dep, cmd, &params);
-	WARN_ON_ONCE(ret);
+	if (ret)
+		dev_err_ratelimited(dwc->dev,
+			"ep0 data phase end transfer failed: %d\n", ret);
+
 	dep->resource_index = 0;
 }
 
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 4a3e97e606d1..4a3d076c1015 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1772,7 +1772,11 @@ static int __dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force, bool int
 		dep->flags |= DWC3_EP_DELAY_STOP;
 		return 0;
 	}
-	WARN_ON_ONCE(ret);
+
+	if (ret)
+		dev_err_ratelimited(dep->dwc->dev,
+				"end transfer failed: %d\n", ret);
+
 	dep->resource_index = 0;
 
 	if (!interrupt)
@@ -4039,7 +4043,9 @@ static void dwc3_clear_stall_all_ep(struct dwc3 *dwc)
 		dep->flags &= ~DWC3_EP_STALL;
 
 		ret = dwc3_send_clear_stall_ep_cmd(dep);
-		WARN_ON_ONCE(ret);
+		if (ret)
+			dev_err_ratelimited(dwc->dev,
+				"failed to clear STALL on %s\n", dep->name);
 	}
 }
 
-- 
2.17.1