linux-kernel - [PATCH v4] usb: core: adds support for PM control of specific USB dev skip suspend.

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Message-Id: <20241023034457.13241-1-huanglei814@163.com>
Date: Wed, 23 Oct 2024 11:44:57 +0800
From: huanglei814 <huanglei814@....com>
To: gregkh@...uxfoundation.org,
	mathias.nyman@...el.com
Cc: linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	huanglei <huanglei@...inos.cn>
Subject: [PATCH v4] usb: core: adds support for PM control of specific USB dev skip suspend.

From: huanglei <huanglei@...inos.cn>

All USB devices are brought into suspend power state after system suspend.
It is desirable for some specific manufacturers buses to keep their devices
in normal state even after system suspend.

Signed-off-by: huanglei <huanglei@...inos.cn>
---
v3->v4:
- Cancel SUSPENDED state judgment when enter suspend，because udev will not enter.
- Change "usb-skip-suspend" to "usb-never-suspend"
- Change dev_err to dev_info.
- Remove Kconfig option, it's redundant indeed.
- Update commit message style.
v2->v3:
- Rebase and update commit message.
v1->v2:
- Change to bool type for skip_suspend.
- Kconfig remove "default n", 'n' is the default.
---
 drivers/usb/core/driver.c    | 8 ++++++++
 drivers/usb/host/xhci-plat.c | 5 +++++
 include/linux/usb.h          | 7 +++++++
 3 files changed, 20 insertions(+)

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 0c3f12daac79..93137c7c34df 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1583,6 +1583,11 @@ int usb_suspend(struct device *dev, pm_message_t msg)
 	struct usb_device	*udev = to_usb_device(dev);
 	int r;
 
+	if (udev->bus->skip_suspend && (msg.event == PM_EVENT_SUSPEND)) {
+		dev_info(dev, "abort suspend\n");
+		return 0;
+	}
+
 	unbind_no_pm_drivers_interfaces(udev);
 
 	/* From now on we are sure all drivers support suspend/resume
@@ -1619,6 +1624,9 @@ int usb_resume(struct device *dev, pm_message_t msg)
 	struct usb_device	*udev = to_usb_device(dev);
 	int			status;
 
+	if (udev->bus->skip_suspend && (msg.event == PM_EVENT_RESUME))
+		return 0;
+
 	/* For all calls, take the device back to full power and
 	 * tell the PM core in case it was autosuspended previously.
 	 * Unbind the interfaces that will need rebinding later,
diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index ecaa75718e59..35062aa19a32 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -265,6 +265,11 @@ int xhci_plat_probe(struct platform_device *pdev, struct device *sysdev, const s
 		if (device_property_read_bool(tmpdev, "xhci-skip-phy-init-quirk"))
 			xhci->quirks |= XHCI_SKIP_PHY_INIT;
 
+		if (device_property_read_bool(tmpdev, "usb-never-suspend")) {
+			hcd_to_bus(hcd)->skip_suspend = true;
+			hcd_to_bus(xhci->shared_hcd)->skip_suspend = true;
+		}
+
 		device_property_read_u32(tmpdev, "imod-interval-ns",
 					 &xhci->imod_interval);
 	}
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 672d8fc2abdb..c854d1f622ec 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -487,6 +487,13 @@ struct usb_bus {
 	struct mon_bus *mon_bus;	/* non-null when associated */
 	int monitored;			/* non-zero when monitored */
 #endif
+
+	bool skip_suspend;		/* All USB devices are brought into suspend
+					 * power state after system suspend. It is
+					 * desirable for some specific manufacturers
+					 * buses to keep their devices in normal
+					 * state even after system suspend.
+					 */
 };
 
 struct usb_dev_state;
-- 
2.17.1