[PATCH v4 3/3] usb: dwc3: Modify runtime pm ops to handle bus suspend

[Elson Roy Serrao]

The current implementation blocks the runtime pm operations when cable
is connected. This would block dwc3 to enter a low power state during
bus suspend scenario. Modify the runtime pm ops to handle bus suspend
case for such platforms where the controller low power mode entry/exit
is handled by the glue driver. This enablement is controlled through a
dt property and platforms capable of detecting bus resume can benefit
from this feature. Also modify the remote wakeup operations to trigger
runtime resume before sending wakeup signal.

Signed-off-by: Elson Roy Serrao <quic_eserrao@xxxxxxxxxxx>
---
 drivers/usb/dwc3/core.c   | 28 ++++++++++++++++++++++++++--
 drivers/usb/dwc3/core.h   |  3 +++
 drivers/usb/dwc3/gadget.c | 32 +++++++++++++++++++++++++-------
 3 files changed, 54 insertions(+), 9 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 9c6bf054f15d..9bfd9bb18caf 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1518,6 +1518,9 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 	dwc->dis_split_quirk = device_property_read_bool(dev,
 				"snps,dis-split-quirk");
 
+	dwc->runtime_suspend_on_usb_suspend = device_property_read_bool(dev,
+				"snps,runtime-suspend-on-usb-suspend");
+
 	dwc->lpm_nyet_threshold = lpm_nyet_threshold;
 	dwc->tx_de_emphasis = tx_de_emphasis;
 
@@ -2029,6 +2032,9 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
 
 	switch (dwc->current_dr_role) {
 	case DWC3_GCTL_PRTCAP_DEVICE:
+		/* runtime resume on bus resume scenario */
+		if (PMSG_IS_AUTO(msg) && dwc->connected)
+			break;
 		ret = dwc3_core_init_for_resume(dwc);
 		if (ret)
 			return ret;
@@ -2090,8 +2096,13 @@ static int dwc3_runtime_checks(struct dwc3 *dwc)
 {
 	switch (dwc->current_dr_role) {
 	case DWC3_GCTL_PRTCAP_DEVICE:
-		if (dwc->connected)
+		if (dwc->connected) {
+			/* bus suspend scenario */
+			if (dwc->runtime_suspend_on_usb_suspend &&
+			    dwc->suspended)
+				break;
 			return -EBUSY;
+		}
 		break;
 	case DWC3_GCTL_PRTCAP_HOST:
 	default:
@@ -2107,9 +2118,22 @@ static int dwc3_runtime_suspend(struct device *dev)
 	struct dwc3     *dwc = dev_get_drvdata(dev);
 	int		ret;
 
-	if (dwc3_runtime_checks(dwc))
+	ret = dwc3_runtime_checks(dwc);
+	if (ret)
 		return -EBUSY;
 
+	switch (dwc->current_dr_role) {
+	case DWC3_GCTL_PRTCAP_DEVICE:
+		/* bus suspend case */
+		if (!ret && dwc->connected)
+			return 0;
+		break;
+	case DWC3_GCTL_PRTCAP_HOST:
+	default:
+		/* do nothing */
+		break;
+	}
+
 	ret = dwc3_suspend_common(dwc, PMSG_AUTO_SUSPEND);
 	if (ret)
 		return ret;
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index a69ac67d89fe..f2f788a6b4b5 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1124,6 +1124,8 @@ struct dwc3_scratchpad_array {
  * @num_ep_resized: carries the current number endpoints which have had its tx
  *		    fifo resized.
  * @debug_root: root debugfs directory for this device to put its files in.
+ * @runtime_suspend_on_usb_suspend: true if dwc3 runtime suspend is allowed
+ *			during bus suspend scenario.
  */
 struct dwc3 {
 	struct work_struct	drd_work;
@@ -1340,6 +1342,7 @@ struct dwc3 {
 	int			last_fifo_depth;
 	int			num_ep_resized;
 	struct dentry		*debug_root;
+	bool			runtime_suspend_on_usb_suspend;
 };
 
 #define INCRX_BURST_MODE 0
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 5fd067151fbf..978ce0e91164 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2401,15 +2401,21 @@ 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_resume_and_get(dwc->dev);
+	if (ret < 0) {
+		pm_runtime_set_suspended(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;
 }
@@ -2428,6 +2434,12 @@ static int dwc3_gadget_func_wakeup(struct usb_gadget *g, int intf_id)
 		return -EINVAL;
 	}
 
+	ret = pm_runtime_resume_and_get(dwc->dev);
+	if (ret < 0) {
+		pm_runtime_set_suspended(dwc->dev);
+		return ret;
+	}
+
 	spin_lock_irqsave(&dwc->lock, flags);
 	/*
 	 * If the link is in U3, signal for remote wakeup and wait for the
@@ -2438,6 +2450,7 @@ 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);
@@ -2452,6 +2465,7 @@ 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;
 }
@@ -2732,21 +2746,23 @@ 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);
 		if (ret < 0)
 			pm_runtime_set_suspended(dwc->dev);
@@ -4331,6 +4347,8 @@ static void dwc3_gadget_suspend_interrupt(struct dwc3 *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,
-- 
2.17.1