[PATCH v3] usb: dwc3: Set the ClearPendIN bit on Clear Stall EP command

[John Youn <johnyoun@xxxxxxxxxxxx>]

As of core revision 2.60a the recommended programming model is to set
the ClearPendIN bit when issuing a Clear Stall EP command for IN
endpoints. This is to prevent an issue where some (non-compliant) hosts
may not send ACK TPs for pending IN transfers due to a mishandled error
condition. Synopsys STAR 9000614252.

Signed-off-by: John Youn <johnyoun@xxxxxxxxxxxx>
---
Hi Felipe,

I rebased this on your testing/fixes. You'll have to fix "usb: dwc3:
gadget: pass dep as argument to endpoint command" on your
testing/next.

Or you can just apply v2 to your testing/next. It's ok if this goes
into 4.8.

Regards,
John

v3:
* Rebased on Felipe's testing/fixes

v2:
* Removed the call to dwc3_is_usb31(). Forgot that we set the high bit
  in the version so that we can just do a comparison for these cases.
* Added documentation in the code.

 drivers/usb/dwc3/core.h   |  1 +
 drivers/usb/dwc3/gadget.c | 30 ++++++++++++++++++++++++------
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 7ddf944..6540506 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -402,6 +402,7 @@
 #define DWC3_DEPCMD_GET_RSC_IDX(x)	(((x) >> DWC3_DEPCMD_PARAM_SHIFT) & 0x7f)
 #define DWC3_DEPCMD_STATUS(x)		(((x) >> 12) & 0x0F)
 #define DWC3_DEPCMD_HIPRI_FORCERM	(1 << 11)
+#define DWC3_DEPCMD_CLEARPENDIN		(1 << 11)
 #define DWC3_DEPCMD_CMDACT		(1 << 10)
 #define DWC3_DEPCMD_CMDIOC		(1 << 8)
 
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 9a7d0bd..07248ff 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -347,6 +347,28 @@ int dwc3_send_gadget_ep_cmd(struct dwc3 *dwc, unsigned ep,
 	return ret;
 }
 
+static int dwc3_send_clear_stall_ep_cmd(struct dwc3_ep *dep)
+{
+	struct dwc3 *dwc = dep->dwc;
+	struct dwc3_gadget_ep_cmd_params params;
+	u32 cmd = DWC3_DEPCMD_CLEARSTALL;
+
+	/*
+	 * As of core revision 2.60a the recommended programming model
+	 * is to set the ClearPendIN bit when issuing a Clear Stall EP
+	 * command for IN endpoints. This is to prevent an issue where
+	 * some (non-compliant) hosts may not send ACK TPs for pending
+	 * IN transfers due to a mishandled error condition. Synopsys
+	 * STAR 9000614252.
+	 */
+	if (dep->direction && (dwc->revision >= DWC3_REVISION_260A))
+		cmd |= DWC3_DEPCMD_CLEARPENDIN;
+
+	memset(&params, 0, sizeof(params));
+
+	return dwc3_send_gadget_ep_cmd(dwc, dep->number, cmd, &params);
+}
+
 static dma_addr_t dwc3_trb_dma_offset(struct dwc3_ep *dep,
 		struct dwc3_trb *trb)
 {
@@ -1314,8 +1336,7 @@ int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value, int protocol)
 		else
 			dep->flags |= DWC3_EP_STALL;
 	} else {
-		ret = dwc3_send_gadget_ep_cmd(dwc, dep->number,
-			DWC3_DEPCMD_CLEARSTALL, &params);
+		ret = dwc3_send_clear_stall_ep_cmd(dep);
 		if (ret)
 			dev_err(dwc->dev, "failed to clear STALL on %s\n",
 					dep->name);
@@ -2247,7 +2268,6 @@ static void dwc3_clear_stall_all_ep(struct dwc3 *dwc)
 
 	for (epnum = 1; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
 		struct dwc3_ep *dep;
-		struct dwc3_gadget_ep_cmd_params params;
 		int ret;
 
 		dep = dwc->eps[epnum];
@@ -2259,9 +2279,7 @@ static void dwc3_clear_stall_all_ep(struct dwc3 *dwc)
 
 		dep->flags &= ~DWC3_EP_STALL;
 
-		memset(&params, 0, sizeof(params));
-		ret = dwc3_send_gadget_ep_cmd(dwc, dep->number,
-				DWC3_DEPCMD_CLEARSTALL, &params);
+		ret = dwc3_send_clear_stall_ep_cmd(dep);
 		WARN_ON_ONCE(ret);
 	}
 }
-- 
2.8.2

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