Messages in this thread Patch in this message | | | Date | Wed, 27 May 2015 10:49:19 +0800 | From | "Zhang, Yanmin" <> | Subject | [PATCH V2 1/3] usb: add function usb_autopm_get_interface_upgrade |
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Some usb driver has a specific requirement. Their critical functions might be called under both atomic environment and non-atomic environment.
If it's under atomic environment, the driver can wake up the device by calling pm_runtime_get_sync directly.
If it's under non-atomic environment, the function's caller need wake up the device before the function accesses the device.
The patch adds usb_autopm_get_interface_upgrade, a new function to support above capability.
Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>
---
drivers/usb/core/driver.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++ include/linux/usb.h | 3 +++ 2 files changed, 57 insertions(+)
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c index 818369a..5d6f9ee 100644 --- a/drivers/usb/core/driver.c +++ b/drivers/usb/core/driver.c @@ -1684,6 +1684,60 @@ int usb_autopm_get_interface(struct usb_interface *intf) EXPORT_SYMBOL_GPL(usb_autopm_get_interface); /** + * usb_autopm_get_interface_upgrade - increment a USB interface's PM-usage + * counter + * @intf: the usb_interface whose counter should be incremented + * + * This routine should be called by an interface driver when it wants to + * use @intf and needs to guarantee that it is not suspended. In addition, + * the routine prevents @intf from being autosuspended subsequently. (Note + * that this will not prevent suspend events originating in the PM core.) + * This prevention will persist until usb_autopm_put_interface() is called + * or @intf is unbound. A typical example would be a character-device + * driver when its device file is opened. + * + * Comparing with usb_autopm_get_interface, usb_autopm_get_interface_upgrade + * is more careful when resuming the device. + * 1) The caller's caller already resumes resume the device and hold spinlocks. + * usb_autopm_get_interface_upgrade couldn't call pm_runtime_get_sync; + * 2) The caller's caller doesn't resume the device. + * usb_autopm_get_interface_upgrade has to resume the device before going ahead. + * + * @intf's usage counter is incremented to prevent subsequent autosuspends. + * However if the autoresume fails then the counter is re-decremented. + * + * This routine can run only in process context. + * + * Return: 0 on success. + */ +int usb_autopm_get_interface_upgrade(struct usb_interface *intf) +{ + int status = 0; + + pm_runtime_get(&intf->dev); + if (!pm_runtime_active(&intf->dev)) { + /* If not active, next _get_sync wakes device up*/ + status = pm_runtime_get_sync(&intf->dev); + /* + * If it's active, next _put_sync wouldn't + * really put it to sleep as the 1st _get + * keeps the device active. + */ + pm_runtime_put_sync(&intf->dev); + if (status < 0) + pm_runtime_put(&intf->dev); + } else + atomic_inc(&intf->pm_usage_cnt); + dev_vdbg(&intf->dev, "%s: cnt %d -> %d\n", + __func__, atomic_read(&intf->dev.power.usage_count), + status); + if (status > 0) + status = 0; + return status; +} +EXPORT_SYMBOL_GPL(usb_autopm_get_interface_upgrade); + +/** * usb_autopm_get_interface_async - increment a USB interface's PM-usage counter * @intf: the usb_interface whose counter should be incremented * diff --git a/include/linux/usb.h b/include/linux/usb.h index 447fe29..0a8a44a 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -663,6 +663,7 @@ extern void usb_enable_autosuspend(struct usb_device *udev); extern void usb_disable_autosuspend(struct usb_device *udev); extern int usb_autopm_get_interface(struct usb_interface *intf); +extern int usb_autopm_get_interface_upgrade(struct usb_interface *intf); extern void usb_autopm_put_interface(struct usb_interface *intf); extern int usb_autopm_get_interface_async(struct usb_interface *intf); extern void usb_autopm_put_interface_async(struct usb_interface *intf); @@ -683,6 +684,8 @@ static inline int usb_disable_autosuspend(struct usb_device *udev) static inline int usb_autopm_get_interface(struct usb_interface *intf) { return 0; } +static inline int usb_autopm_get_interface_upgrade(struct usb_interface *intf) +{ return 0; } static inline int usb_autopm_get_interface_async(struct usb_interface *intf) { return 0; } -- 1.9.1
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