linux-kernel - [PATCH v1] usb: dwc3: core: Avoid redundant system suspend/resume callbacks

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Message-ID: <20250304000458.1826450-1-royluo@google.com>
Date: Tue,  4 Mar 2025 00:04:58 +0000
From: Roy Luo <royluo@...gle.com>
To: royluo@...gle.com, Thinh.Nguyen@...opsys.com, gregkh@...uxfoundation.org, 
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v1] usb: dwc3: core: Avoid redundant system suspend/resume callbacks

dwc3 device suspend/resume callbacks were being triggered during system
suspend and resume even if the device was already runtime-suspended.
This is redundant for device mode because the suspend and resume routines
are essentially identical for system PM and runtime PM. The minor
difference in pinctrl state changes has been moved to the common section
in this patch.
To prevent these unnecessary callbacks, indicate to the PM core that it
can safely leave the device in runtime suspend if it's already
runtime-suspended in device mode by returning a positive value in
prepare() callback.

Signed-off-by: Roy Luo <royluo@...gle.com>
---
 drivers/usb/dwc3/core.c | 27 ++++++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index dfa1b5fe48dc..b83f094ff1c5 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -2398,10 +2398,12 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
 		dwc3_gadget_suspend(dwc);
 		synchronize_irq(dwc->irq_gadget);
 		dwc3_core_exit(dwc);
+		pinctrl_pm_select_sleep_state(dwc->dev);
 		break;
 	case DWC3_GCTL_PRTCAP_HOST:
 		if (!PMSG_IS_AUTO(msg) && !device_may_wakeup(dwc->dev)) {
 			dwc3_core_exit(dwc);
+			pinctrl_pm_select_sleep_state(dwc->dev);
 			break;
 		}
 
@@ -2436,6 +2438,7 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
 
 		dwc3_otg_exit(dwc);
 		dwc3_core_exit(dwc);
+		pinctrl_pm_select_sleep_state(dwc->dev);
 		break;
 	default:
 		/* do nothing */
@@ -2453,6 +2456,7 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
 
 	switch (dwc->current_dr_role) {
 	case DWC3_GCTL_PRTCAP_DEVICE:
+		pinctrl_pm_select_default_state(dwc->dev);
 		ret = dwc3_core_init_for_resume(dwc);
 		if (ret)
 			return ret;
@@ -2462,6 +2466,7 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
 		break;
 	case DWC3_GCTL_PRTCAP_HOST:
 		if (!PMSG_IS_AUTO(msg) && !device_may_wakeup(dwc->dev)) {
+			pinctrl_pm_select_default_state(dwc->dev);
 			ret = dwc3_core_init_for_resume(dwc);
 			if (ret)
 				return ret;
@@ -2490,6 +2495,7 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
 		if (PMSG_IS_AUTO(msg))
 			break;
 
+		pinctrl_pm_select_default_state(dwc->dev);
 		ret = dwc3_core_init_for_resume(dwc);
 		if (ret)
 			return ret;
@@ -2608,8 +2614,6 @@ static int dwc3_suspend(struct device *dev)
 	if (ret)
 		return ret;
 
-	pinctrl_pm_select_sleep_state(dev);
-
 	return 0;
 }
 
@@ -2618,8 +2622,6 @@ static int dwc3_resume(struct device *dev)
 	struct dwc3	*dwc = dev_get_drvdata(dev);
 	int		ret = 0;
 
-	pinctrl_pm_select_default_state(dev);
-
 	pm_runtime_disable(dev);
 	ret = pm_runtime_set_active(dev);
 	if (ret)
@@ -2647,14 +2649,29 @@ static void dwc3_complete(struct device *dev)
 		dwc3_writel(dwc->regs, DWC3_GUCTL3, reg);
 	}
 }
+
+static int dwc3_prepare(struct device *dev)
+{
+	struct dwc3	*dwc = dev_get_drvdata(dev);
+
+	/*
+	 * Indicate to the PM core that it may safely leave the device in
+	 * runtime suspend if runtime-suspended already in device mode.
+	 */
+	if (dwc->current_dr_role == DWC3_GCTL_PRTCAP_DEVICE)
+		return 1;
+
+	return 0;
+}
 #else
 #define dwc3_complete NULL
+#define dwc3_prepare NULL
 #endif /* CONFIG_PM_SLEEP */
 
 static const struct dev_pm_ops dwc3_dev_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(dwc3_suspend, dwc3_resume)
 	.complete = dwc3_complete,
-
+	.prepare = dwc3_prepare,
 	/*
 	 * Runtime suspend halts the controller on disconnection. It relies on
 	 * platforms with custom connection notification to start the controller

base-commit: 99fa936e8e4f117d62f229003c9799686f74cebc
-- 
2.48.1.711.g2feabab25a-goog