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Chances are when the main processor decides to suspend the USB device, the USB device might still be used by the co-processor. In this scenario, we need a way to let system know whether it can suspend the USB device or not. We introduce a new sysfs entry "deprecate_device_pm" to allow userspace to control the device power management functionality on demand. As the userspace should possess the information of both the main processor and the co-processor, it should be able to address the conflict mentioned above. Signed-off-by: Guan-Yu Lin --- Documentation/ABI/testing/sysfs-bus-usb | 10 +++++++++ drivers/usb/core/driver.c | 18 ++++++++++++++++ drivers/usb/core/sysfs.c | 28 +++++++++++++++++++++++++ drivers/usb/host/xhci-plat.c | 20 ++++++++++++++++++ include/linux/usb.h | 4 ++++ 5 files changed, 80 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb index 2b7108e21977..3f3d6c14201f 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/deprecate_device_pm +Date: January 2024 +Contact: Guan-Yu Lin +Description: + Deprecates the device power management functionality of 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..e03cf972160d 100644 --- a/drivers/usb/core/driver.c +++ b/drivers/usb/core/driver.c @@ -1569,6 +1569,15 @@ int usb_suspend(struct device *dev, pm_message_t msg) struct usb_device *udev = to_usb_device(dev); int r; + /* + * Skip the entire suspend process under the same usb bus if its sysfs + * entry `deprecate_device_pm` is set. + */ + if (udev->bus->deprecate_device_pm) { + dev_vdbg(&udev->dev, "deprecating dev_pm_ops: %s\n", __func__); + return 0; + } + unbind_no_pm_drivers_interfaces(udev); /* From now on we are sure all drivers support suspend/resume @@ -1605,6 +1614,15 @@ int usb_resume(struct device *dev, pm_message_t msg) struct usb_device *udev = to_usb_device(dev); int status; + /* + * Skip the entire resume process under the same usb bus if its sysfs + * entry `deprecate_device_pm` is set. + */ + if (udev->bus->deprecate_device_pm) { + dev_vdbg(&udev->dev, "deprecating dev_pm_ops: %s\n", __func__); + 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..b4520e5c8974 100644 --- a/drivers/usb/core/sysfs.c +++ b/drivers/usb/core/sysfs.c @@ -68,6 +68,33 @@ static ssize_t bMaxPower_show(struct device *dev, } static DEVICE_ATTR_RO(bMaxPower); +static ssize_t deprecate_device_pm_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->deprecate_device_pm)); +} + +static ssize_t deprecate_device_pm_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct usb_device *udev = to_usb_device(dev); + int val, rc; + + if (sscanf(buf, "%d", &val) != 1 || val < 0 || val > 1) + return -EINVAL; + rc = usb_lock_device_interruptible(udev); + if (rc < 0) + return -EINTR; + udev->bus->deprecate_device_pm = !!(val); + usb_unlock_device(udev); + return count; +} +static DEVICE_ATTR_RW(deprecate_device_pm); + static ssize_t configuration_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -984,6 +1011,7 @@ 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_deprecate_device_pm.attr, NULL, }; diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c index f04fde19f551..bc05d83d1c0b 100644 --- a/drivers/usb/host/xhci-plat.c +++ b/drivers/usb/host/xhci-plat.c @@ -442,6 +442,15 @@ static int xhci_plat_suspend(struct device *dev) struct xhci_hcd *xhci = hcd_to_xhci(hcd); int ret; + /* + * Skip the entire suspend process under the same usb bus if its sysfs + * entry `deprecate_device_pm` is set. + */ + if (hcd->self.deprecate_device_pm) { + dev_vdbg(dev, "deprecating dev_pm_ops: %s\n", __func__); + return 0; + } + if (pm_runtime_suspended(dev)) pm_runtime_resume(dev); @@ -507,6 +516,17 @@ static int xhci_plat_resume_common(struct device *dev, struct pm_message pmsg) static int xhci_plat_resume(struct device *dev) { + struct usb_hcd *hcd = dev_get_drvdata(dev); + + /* + * Skip the entire resume process under the same usb bus if its sysfs + * entry `deprecate_device_pm` is set. + */ + if (hcd->self.deprecate_device_pm) { + dev_vdbg(dev, "deprecating dev_pm_ops: %s\n", __func__); + return 0; + } + return xhci_plat_resume_common(dev, PMSG_RESUME); } diff --git a/include/linux/usb.h b/include/linux/usb.h index 9e52179872a5..1a1873104663 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 deprecate_device_pm:1; /* Deprecates the device power management + * functionality 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 */ -- 2.43.0.429.g432eaa2c6b-goog