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USB: Export if an interface driver supports autosuspend.

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Create a new sysfs file per interface named supports_autosuspend.  This
file returns true if an interface driver's .supports_autosuspend flag is
set.  It also returns true if the interface is unclaimed (since the USB
core will autosuspend a device if an interface is not claimed).

This new sysfs file will be useful for user space scripts to test whether
a USB device correctly auto-suspends.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Sarah Sharp 2008-10-06 14:45:46 -07:00 committed by Greg Kroah-Hartman
parent eafe5b99f2
commit 49e7cc84a8
2 changed files with 40 additions and 0 deletions
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16
Documentation/ABI/testing/sysfs-bus-usb
View File

@ -85,3 +85,19 @@ Description:
Users:
PowerTOP <power@bughost.org>
http://www.lesswatts.org/projects/powertop/
What: /sys/bus/usb/device/<busnum>-<devnum>...:<config num>-<interface num>/supports_autosuspend
Date: January 2008
KernelVersion: 2.6.27
Contact: Sarah Sharp <sarah.a.sharp@intel.com>
Description:
When read, this file returns 1 if the interface driver
for this interface supports autosuspend. It also
returns 1 if no driver has claimed this interface, as an
unclaimed interface will not stop the device from being
autosuspended if all other interface drivers are idle.
The file returns 0 if autosuspend support has not been
added to the driver.
Users:
USB PM tool
git://git.moblin.org/users/sarah/usb-pm-tool/

24
drivers/usb/core/sysfs.c
View File

@ -743,6 +743,29 @@ static ssize_t show_modalias(struct device *dev,
}
static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL);
static ssize_t show_supports_autosuspend(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct usb_interface *intf;
struct usb_device *udev;
int ret;
intf = to_usb_interface(dev);
udev = interface_to_usbdev(intf);
usb_lock_device(udev);
/* Devices will be autosuspended even when an interface isn't claimed */
if (!intf->dev.driver ||
to_usb_driver(intf->dev.driver)->supports_autosuspend)
ret = sprintf(buf, "%u\n", 1);
else
ret = sprintf(buf, "%u\n", 0);
usb_unlock_device(udev);
return ret;
}
static DEVICE_ATTR(supports_autosuspend, S_IRUGO, show_supports_autosuspend, NULL);
static struct attribute *intf_attrs[] = {
&dev_attr_bInterfaceNumber.attr,
&dev_attr_bAlternateSetting.attr,
@ -751,6 +774,7 @@ static struct attribute *intf_attrs[] = {
&dev_attr_bInterfaceSubClass.attr,
&dev_attr_bInterfaceProtocol.attr,
&dev_attr_modalias.attr,
&dev_attr_supports_autosuspend.attr,
NULL,
};
static struct attribute_group intf_attr_grp = {