In systems with both a main processor and a co-processor, asynchronous
controller management can lead to conflicts. For example, the main
processor might attempt to suspend a USB device while the co-processor
is actively transferring data. To address this, we introduce a new
sysfs entry, "disable_suspend2ram", which allows userspace to control
the suspend-to-RAM functionality of devices on a specific USB bus.
Since the userspace has visibility into the activities of both
processors, it can resolve potential conflicts.
Signed-off-by: Guan-Yu Lin <guanyulin@xxxxxxxxxx>
---
Documentation/ABI/testing/sysfs-bus-usb | 10 +++++++
drivers/usb/core/driver.c | 12 ++++++++
drivers/usb/core/sysfs.c | 29 ++++++++++++++++++
drivers/usb/host/xhci-plat.c | 40 ++++++++++++++++++++++---
include/linux/usb.h | 4 +++
5 files changed, 91 insertions(+), 4 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index 2b7108e21977..f6a4f496c8f6 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -19,6 +19,16 @@ Description:
would be authorized by default.
The value can be 1 or 0. It's by default 1.
+What: /sys/bus/usb/devices/usbX/disable_suspend2ram
+Date: January 2024
+Contact: Guan-Yu Lin <guanyulin@xxxxxxxxxx>
+Description:
+ Disables "suspend-to-RAM" system power management in USB devices
+ and their host contorller under this usb bus. The modification of
+ this entry should be done when the system is active to ensure the
+ correctness of system power state transitions.
+ The value can be 1 or 0. It's by default 0.
+
What: /sys/bus/usb/device/.../authorized
Date: July 2008
KernelVersion: 2.6.26
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index e02ba15f6e34..c555e2b1ddda 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1569,6 +1569,12 @@ int usb_suspend(struct device *dev, pm_message_t msg)
struct usb_device *udev = to_usb_device(dev);
int r;
+ if (msg.event == PM_EVENT_SUSPEND && udev->bus->disable_suspend2ram) {
+ /* Skip "suspend-to-RAM" process under the same USB bus */
+ dev_dbg(dev, "suspend-to-RAM disabled, skipping dev_pm_ops.suspend\n");
+ return 0;
+ }
+
unbind_no_pm_drivers_interfaces(udev);
/* From now on we are sure all drivers support suspend/resume
@@ -1605,6 +1611,12 @@ int usb_resume(struct device *dev, pm_message_t msg)
struct usb_device *udev = to_usb_device(dev);
int status;
+ if (msg.event == PM_EVENT_RESUME && udev->bus->disable_suspend2ram) {
+ /* Skip "suspend-to-RAM" process under the same USB bus */
+ dev_dbg(dev, "suspend-to-RAM disabled, skipping dev_pm_ops.resume\n");
+ 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/core/sysfs.c b/drivers/usb/core/sysfs.c
index 5d21718afb05..7a228ea95506 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -68,6 +68,34 @@ static ssize_t bMaxPower_show(struct device *dev,
}
static DEVICE_ATTR_RO(bMaxPower);
+static ssize_t disable_suspend2ram_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct usb_device *udev;
+
+ udev = to_usb_device(dev);
+ return sysfs_emit(buf, "%d\n", !!(udev->bus->disable_suspend2ram));
+}
+
+static ssize_t disable_suspend2ram_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct usb_device *udev = to_usb_device(dev);
+ bool val;
+ int rc;
+
+ if (kstrtobool(buf, &val) != 0)
+ return -EINVAL;
+ rc = usb_lock_device_interruptible(udev);
+ if (rc < 0)
+ return -EINTR;
+ udev->bus->disable_suspend2ram = !!(val);
+ usb_unlock_device(udev);
+ return count;
+}
+static DEVICE_ATTR_RW(disable_suspend2ram);
+
static ssize_t configuration_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@@ -984,6 +1012,7 @@ static DEVICE_ATTR_RW(interface_authorized_default);
static struct attribute *usb_bus_attrs[] = {
&dev_attr_authorized_default.attr,
&dev_attr_interface_authorized_default.attr,
+ &dev_attr_disable_suspend2ram.attr,
NULL,
};
diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index f04fde19f551..86733249fcdc 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -436,12 +436,18 @@ void xhci_plat_remove(struct platform_device *dev)
}
EXPORT_SYMBOL_GPL(xhci_plat_remove);
-static int xhci_plat_suspend(struct device *dev)
+static int xhci_plat_suspend_common(struct device *dev, struct pm_message pmsg)
{
struct usb_hcd *hcd = dev_get_drvdata(dev);
struct xhci_hcd *xhci = hcd_to_xhci(hcd);
int ret;
+ if (pmsg.event == PM_EVENT_SUSPEND && hcd->self.disable_suspend2ram) {
+ /* Skip "suspend-to-RAM" process under the same USB bus */
+ dev_dbg(dev, "suspend-to-RAM disabled, skipping dev_pm_ops.suspend\n");
+ return 0;
+ }
+
if (pm_runtime_suspended(dev))
pm_runtime_resume(dev);
@@ -464,12 +470,33 @@ static int xhci_plat_suspend(struct device *dev)
return 0;
}
+static int xhci_plat_suspend(struct device *dev)
+{
+ return xhci_plat_suspend_common(dev, PMSG_SUSPEND);
+}
+
+static int xhci_plat_freeze(struct device *dev)
+{
+ return xhci_plat_suspend_common(dev, PMSG_FREEZE);
+}
+
+static int xhci_plat_poweroff(struct device *dev)
+{
+ return xhci_plat_suspend_common(dev, PMSG_HIBERNATE);
+}
+
static int xhci_plat_resume_common(struct device *dev, struct pm_message pmsg)
{
struct usb_hcd *hcd = dev_get_drvdata(dev);
struct xhci_hcd *xhci = hcd_to_xhci(hcd);
int ret;
+ if (pmsg.event == PM_EVENT_RESUME && hcd->self.disable_suspend2ram) {
+ /* Skip "suspend-to-RAM" process under the same USB bus */
+ dev_dbg(dev, "suspend-to-RAM disabled, skipping dev_pm_ops.resume\n");
+ return 0;
+ }
+
if (!device_may_wakeup(dev) && (xhci->quirks & XHCI_SUSPEND_RESUME_CLKS)) {
ret = clk_prepare_enable(xhci->clk);
if (ret)
@@ -510,6 +537,11 @@ static int xhci_plat_resume(struct device *dev)
return xhci_plat_resume_common(dev, PMSG_RESUME);
}
+static int xhci_plat_thaw(struct device *dev)
+{
+ return xhci_plat_resume_common(dev, PMSG_THAW);
+}
+
static int xhci_plat_restore(struct device *dev)
{
return xhci_plat_resume_common(dev, PMSG_RESTORE);
@@ -539,9 +571,9 @@ static int __maybe_unused xhci_plat_runtime_resume(struct device *dev)
const struct dev_pm_ops xhci_plat_pm_ops = {
.suspend = pm_sleep_ptr(xhci_plat_suspend),
.resume = pm_sleep_ptr(xhci_plat_resume),
- .freeze = pm_sleep_ptr(xhci_plat_suspend),
- .thaw = pm_sleep_ptr(xhci_plat_resume),
- .poweroff = pm_sleep_ptr(xhci_plat_suspend),
+ .freeze = pm_sleep_ptr(xhci_plat_freeze),
+ .thaw = pm_sleep_ptr(xhci_plat_thaw),
+ .poweroff = pm_sleep_ptr(xhci_plat_poweroff),
.restore = pm_sleep_ptr(xhci_plat_restore),
SET_RUNTIME_PM_OPS(xhci_plat_runtime_suspend,
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 9e52179872a5..a3b8f799c5a4 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -465,6 +465,10 @@ struct usb_bus {
* the ep queue on a short transfer
* with the URB_SHORT_NOT_OK flag set.
*/
+ unsigned disable_suspend2ram:1; /* Disables the "suspend-to-RAM" system
+ * power management of USB devices on this
+ * bus and their hcd.
+ */
unsigned no_sg_constraint:1; /* no sg constraint */
unsigned sg_tablesize; /* 0 or largest number of sg list entries */
--
2.43.0.594.gd9cf4e227d-goog
