linux-kernel - [PATCH v3] usb: dwc3: gadget: Avoid duplicate requests to enable Run/Stop

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Date:   Wed, 27 Jul 2022 19:06:47 -0700
From:   Wesley Cheng <quic_wcheng@...cinc.com>
To:     <balbi@...nel.org>, <gregkh@...uxfoundation.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <quic_jackp@...cinc.com>, <quic_mrana@...cinc.com>,
        <Thinh.Nguyen@...opsys.com>, Wesley Cheng <quic_wcheng@...cinc.com>
Subject: [PATCH v3] usb: dwc3: gadget: Avoid duplicate requests to enable Run/Stop

Relocate the pullups_connected check until after it is ensured that there
are no runtime PM transitions.  If another context triggered the DWC3
core's runtime resume, it may have already enabled the Run/Stop.  Do not
re-run the entire pullup sequence again, as it may issue a core soft
reset while Run/Stop is already set.

This patch depends on
  commit 69e131d1ac4e ("usb: dwc3: gadget: Prevent repeat pullup()")

Fixes: 77adb8bdf422 ("usb: dwc3: gadget: Allow runtime suspend if UDC
unbinded")
Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
---
Changes in v3:
- Ensure to balance out get vote if we exit early

Changes in v2:
- Added fixes and depends on tags

 drivers/usb/dwc3/gadget.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index aeeec751c53c..eca945feeec3 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2539,9 +2539,6 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 
 	is_on = !!is_on;
 
-	if (dwc->pullups_connected == is_on)
-		return 0;
-
 	dwc->softconnect = is_on;
 
 	/*
@@ -2566,6 +2563,11 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 		return 0;
 	}
 
+	if (dwc->pullups_connected == is_on) {
+		pm_runtime_put(dwc->dev);
+		return 0;
+	}
+
 	if (!is_on) {
 		ret = dwc3_gadget_soft_disconnect(dwc);
 	} else {