linux-kernel - [PATCH v3] usb: dwc3: Wait unconditionally after issuing EndXfer command

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Date: Thu, 2 May 2024 10:11:03 +0530
From: Prashanth K <quic_prashk@...cinc.com>
To: Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Greg Kroah-Hartman
	<gregkh@...uxfoundation.org>
CC: Wesley Cheng <quic_wcheng@...cinc.com>, <linux-kernel@...r.kernel.org>,
        <linux-usb@...r.kernel.org>, Prashanth K <quic_prashk@...cinc.com>,
        <stable@...r.kernel.org>
Subject: [PATCH v3] usb: dwc3: Wait unconditionally after issuing EndXfer command

Currently all controller IP/revisions except DWC3_usb3 >= 310a
wait 1ms unconditionally for ENDXFER completion when IOC is not
set. This is because DWC_usb3 controller revisions >= 3.10a
supports GUCTL2[14: Rst_actbitlater] bit which allows polling
CMDACT bit to know whether ENDXFER command is completed.

Consider a case where an IN request was queued, and parallelly
soft_disconnect was called (due to ffs_epfile_release). This
eventually calls stop_active_transfer with IOC cleared, hence
send_gadget_ep_cmd() skips waiting for CMDACT cleared during
EndXfer. For DWC3 controllers with revisions >= 310a, we don't
forcefully wait for 1ms either, and we proceed by unmapping the
requests. If ENDXFER didn't complete by this time, it leads to
SMMU faults since the controller would still be accessing those
requests.

Fix this by ensuring ENDXFER completion by adding 1ms delay in
__dwc3_stop_active_transfer() unconditionally.

Cc: <stable@...r.kernel.org>
Fixes: b353eb6dc285 ("usb: dwc3: gadget: Skip waiting for CMDACT cleared during endxfer")
Signed-off-by: Prashanth K <quic_prashk@...cinc.com>
Acked-by: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
---
Changes in v3:
Fixed build errors by removing unused variable 'dwc'.

Changes in v2:
Changed the patch logic from CMDACT polling to 1ms mdelay.
Updated subject and commit accordingly.
Link to v1: https://lore.kernel.org/all/20240422090539.3986723-1-quic_prashk@quicinc.com/

 drivers/usb/dwc3/gadget.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 4df2661f6675..140120953c76 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1699,7 +1699,6 @@ static int __dwc3_gadget_get_frame(struct dwc3 *dwc)
  */
 static int __dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force, bool interrupt)
 {
-	struct dwc3 *dwc = dep->dwc;
 	struct dwc3_gadget_ep_cmd_params params;
 	u32 cmd;
 	int ret;
@@ -1724,8 +1723,7 @@ static int __dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force, bool int
 	dep->resource_index = 0;

 	if (!interrupt) {
-		if (!DWC3_IP_IS(DWC3) || DWC3_VER_IS_PRIOR(DWC3, 310A))
-			mdelay(1);
+		mdelay(1);
 		dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
 	} else if (!ret) {
 		dep->flags |= DWC3_EP_END_TRANSFER_PENDING;
-- 
2.25.1