linux-kernel - [PATCH v2 1/2] usb: dwc3: gadget: Allow runtime suspend if UDC unbinded

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Message-Id: <20201105232825.5233-2-wcheng@codeaurora.org>
Date:   Thu,  5 Nov 2020 15:28:24 -0800
From:   Wesley Cheng <wcheng@...eaurora.org>
To:     balbi@...nel.org, gregkh@...uxfoundation.org,
        stern@...land.harvard.edu, Thinh.Nguyen@...opsys.com
Cc:     linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        jackp@...eaurora.org, Wesley Cheng <wcheng@...eaurora.org>
Subject: [PATCH v2 1/2] usb: dwc3: gadget: Allow runtime suspend if UDC unbinded

The DWC3 runtime suspend routine checks for the USB connected parameter to
determine if the controller can enter into a low power state.  The
connected state is only set to false after receiving a disconnect event.
However, in the case of a device initiated disconnect (i.e. UDC unbind),
the controller is halted and a disconnect event is never generated.  Set
the connected flag to false if issuing a device initiated disconnect to
allow the controller to be suspended.

Signed-off-by: Wesley Cheng <wcheng@...eaurora.org>
---
 drivers/usb/dwc3/gadget.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 5d879b7606d5..babf977cadc0 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2012,6 +2012,17 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 		}
 	}
 
+	/*
+	 * Check the return value for successful resume, or error.  For a
+	 * successful resume, the DWC3 runtime PM resume routine will handle
+	 * the run stop sequence, so avoid duplicate operations here.
+	 */
+	ret = pm_runtime_get_sync(dwc->dev);
+	if (!ret || ret < 0) {
+		pm_runtime_put(dwc->dev);
+		return 0;
+	}
+
 	/*
 	 * Synchronize any pending event handling before executing the controller
 	 * halt routine.
@@ -2050,10 +2061,12 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 			dwc->ev_buf->lpos = (dwc->ev_buf->lpos + count) %
 						dwc->ev_buf->length;
 		}
+		dwc->connected = false;
 	}
 
 	ret = dwc3_gadget_run_stop(dwc, is_on, false);
 	spin_unlock_irqrestore(&dwc->lock, flags);
+	pm_runtime_put(dwc->dev);
 
 	return ret;
 }
-- 
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