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From:   Elson Roy Serrao <quic_eserrao@quicinc.com>
To:     gregkh@linuxfoundation.org, Thinh.Nguyen@synopsys.com
Cc:     linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
        quic_wcheng@quicinc.com, quic_jackp@quicinc.com,
        Elson Roy Serrao <quic_eserrao@quicinc.com>
Subject: [PATCH 2/2] usb: dwc3: Modify runtime pm ops to handle bus suspend
Date:   Thu, 11 May 2023 10:48:31 -0700
Message-Id: <1683827311-1462-3-git-send-email-quic_eserrao@quicinc.com>
In-Reply-To: <1683827311-1462-1-git-send-email-quic_eserrao@quicinc.com>
References: <1683827311-1462-1-git-send-email-quic_eserrao@quicinc.com>
Precedence: bulk

For bus suspend scenario we should skip controller halt
as we still have the usb cable connected. So modify the
runtime pm ops to handle bus suspend scenario. Also invoke
autosuspend when device receives U3 notification so that
controller can enter runtime suspended state. Ensure that
the controller is brought out of runtime suspend before
triggering remote wakeup.

Signed-off-by: Elson Roy Serrao <quic_eserrao@quicinc.com>
---
 drivers/usb/dwc3/core.c   | 19 +++++++++++++++++++
 drivers/usb/dwc3/gadget.c | 40 +++++++++++++++++++++++++++++++++-------
 2 files changed, 52 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 0beaab9..b00d1e8 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -2108,6 +2108,12 @@ static int dwc3_runtime_suspend(struct device *dev)
 {
 	struct dwc3     *dwc = dev_get_drvdata(dev);
 	int		ret;
+	u32		reg;
+
+	reg = dwc3_readl(dwc->regs, DWC3_DSTS);
+	/* For bus suspend case do not halt the controller */
+	if (DWC3_DSTS_USBLNKST(reg) == DWC3_LINK_STATE_U3 && dwc->connected)
+		return 0;
 
 	if (dwc3_runtime_checks(dwc))
 		return -EBUSY;
@@ -2124,6 +2130,13 @@ static int dwc3_runtime_resume(struct device *dev)
 	struct dwc3     *dwc = dev_get_drvdata(dev);
 	int		ret;
 
+	/* resume from bus suspend */
+	if (dwc->connected) {
+		dwc3_gadget_process_pending_events(dwc);
+		pm_runtime_mark_last_busy(dev);
+		return 0;
+	}
+
 	ret = dwc3_resume_common(dwc, PMSG_AUTO_RESUME);
 	if (ret)
 		return ret;
@@ -2146,9 +2159,14 @@ static int dwc3_runtime_resume(struct device *dev)
 static int dwc3_runtime_idle(struct device *dev)
 {
 	struct dwc3     *dwc = dev_get_drvdata(dev);
+	u32		reg;
 
 	switch (dwc->current_dr_role) {
 	case DWC3_GCTL_PRTCAP_DEVICE:
+		reg = dwc3_readl(dwc->regs, DWC3_DSTS);
+		/* for bus suspend case return success */
+		if (DWC3_DSTS_USBLNKST(reg) == DWC3_LINK_STATE_U3 && dwc->connected)
+			goto autosuspend;
 		if (dwc3_runtime_checks(dwc))
 			return -EBUSY;
 		break;
@@ -2158,6 +2176,7 @@ static int dwc3_runtime_idle(struct device *dev)
 		break;
 	}
 
+autosuspend:
 	pm_runtime_mark_last_busy(dev);
 	pm_runtime_autosuspend(dev);
 
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index c0ca4d1..d4da83b 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2400,15 +2400,21 @@ static int dwc3_gadget_wakeup(struct usb_gadget *g)
 		return -EINVAL;
 	}
 
-	spin_lock_irqsave(&dwc->lock, flags);
 	if (!dwc->gadget->wakeup_armed) {
 		dev_err(dwc->dev, "not armed for remote wakeup\n");
-		spin_unlock_irqrestore(&dwc->lock, flags);
 		return -EINVAL;
 	}
-	ret = __dwc3_gadget_wakeup(dwc, true);
 
+	ret = pm_runtime_get_sync(dwc->dev);
+	if (ret) {
+		pm_runtime_put(dwc->dev);
+		return ret;
+	}
+
+	spin_lock_irqsave(&dwc->lock, flags);
+	ret = __dwc3_gadget_wakeup(dwc, true);
 	spin_unlock_irqrestore(&dwc->lock, flags);
+	pm_runtime_put_noidle(dwc->dev);
 
 	return ret;
 }
@@ -2427,6 +2433,12 @@ static int dwc3_gadget_func_wakeup(struct usb_gadget *g, int intf_id)
 		return -EINVAL;
 	}
 
+	ret = pm_runtime_get_sync(dwc->dev);
+	if (ret) {
+		pm_runtime_put(dwc->dev);
+		return ret;
+	}
+
 	spin_lock_irqsave(&dwc->lock, flags);
 	/*
 	 * If the link is in U3, signal for remote wakeup and wait for the
@@ -2437,6 +2449,7 @@ static int dwc3_gadget_func_wakeup(struct usb_gadget *g, int intf_id)
 		ret = __dwc3_gadget_wakeup(dwc, false);
 		if (ret) {
 			spin_unlock_irqrestore(&dwc->lock, flags);
+			pm_runtime_put_noidle(dwc->dev);
 			return -EINVAL;
 		}
 		dwc3_resume_gadget(dwc);
@@ -2450,6 +2463,7 @@ static int dwc3_gadget_func_wakeup(struct usb_gadget *g, int intf_id)
 		dev_err(dwc->dev, "function remote wakeup failed, ret:%d\n", ret);
 
 	spin_unlock_irqrestore(&dwc->lock, flags);
+	pm_runtime_put_noidle(dwc->dev);
 
 	return ret;
 }
@@ -2711,21 +2725,23 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 	/*
 	 * Avoid issuing a runtime resume if the device is already in the
 	 * suspended state during gadget disconnect.  DWC3 gadget was already
-	 * halted/stopped during runtime suspend.
+	 * halted/stopped during runtime suspend except for bus suspend case
+	 * where we would have skipped the controller halt.
 	 */
 	if (!is_on) {
 		pm_runtime_barrier(dwc->dev);
-		if (pm_runtime_suspended(dwc->dev))
+		if (pm_runtime_suspended(dwc->dev) && !dwc->connected)
 			return 0;
 	}
 
 	/*
 	 * 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.
+	 * the run stop sequence except for bus resume case, so avoid
+	 * duplicate operations here.
 	 */
 	ret = pm_runtime_get_sync(dwc->dev);
-	if (!ret || ret < 0) {
+	if ((!ret && !dwc->connected) || ret < 0) {
 		pm_runtime_put(dwc->dev);
 		return 0;
 	}
@@ -4307,6 +4323,8 @@ static void dwc3_gadget_suspend_interrupt(struct dwc3 *dwc,
 		dwc3_suspend_gadget(dwc);
 
 	dwc->link_state = next;
+	pm_runtime_mark_last_busy(dwc->dev);
+	pm_request_autosuspend(dwc->dev);
 }
 
 static void dwc3_gadget_interrupt(struct dwc3 *dwc,
@@ -4697,7 +4715,15 @@ void dwc3_gadget_process_pending_events(struct dwc3 *dwc)
 {
 	if (dwc->pending_events) {
 		dwc3_interrupt(dwc->irq_gadget, dwc->ev_buf);
+		pm_runtime_put(dwc->dev);
 		dwc->pending_events = false;
 		enable_irq(dwc->irq_gadget);
+		/*
+		 * We have only stored the pending events as part
+		 * of dwc3_interrupt() above, but those events are
+		 * not yet handled. So explicitly invoke the
+		 * interrupt handler for handling those events.
+		 */
+		dwc3_thread_interrupt(dwc->irq_gadget, dwc->ev_buf);
 	}
 }
-- 
2.7.4