On Thu, 15 Mar 2007, Oliver Neukum wrote:
> Am Donnerstag, 15. März 2007 14:31 schrieb Alan Stern:
> > Oliver:
> >
> > Suppose the superuser has suspended a USB device and disabled autoresume.
> > Then what should happen under the following circumstances?
> >
> > 1. The device's usbfs file is opened (or already was open
> > and now gets accessed).
> >
> > 2. The user writes to the bConfigurationValue attribute.
>
> The first two, yes they should. You get what you asked for.
>
> > 3. A new driver module is loaded and it is probed for one
> > of the device's interfaces.
>
> I am not sure. Consequently waking up the device would cause probe
> to be called again, but this seems overkill.
Here's a patch to implement all this. I'm still not crazy about the idea
of disabling autoresume, but I can see that some people might want to do
it occasionally.
This patch is meant to go on top of Greg's latest development patchset,
the 2.6.21-rc3-git9 version. Tell me what you think.
Alan Stern
Index: usb-2.6/Documentation/ABI/testing/sysfs-bus-usb
===================================================================
--- usb-2.6.orig/Documentation/ABI/testing/sysfs-bus-usb
+++ usb-2.6/Documentation/ABI/testing/sysfs-bus-usb
@@ -13,3 +13,29 @@ Description:
The autosuspend delay for newly-created devices is set to
the value of the usbcore.autosuspend module parameter.
+
+What: /sys/bus/usb/devices/.../power/level
+Date: March 2007
+KernelVersion: 2.6.21
+Contact: Alan Stern <[EMAIL PROTECTED]>
+Description:
+ Each USB device directory will contain a file named
+ power/level. This file holds a power-level setting for
+ the device, one of "on", "auto", or "suspend".
+
+ "on" means that the device is not allowed to autosuspend,
+ although normal suspends for system sleep will still
+ be honored. "auto" means the device will autosuspend
+ and autoresume in the usual manner, according to the
+ capabilities of its driver. "suspend" means the device
+ is forced into a suspended state and it will not autoresume
+ in response to I/O requests. However remote-wakeup requests
+ from the device may still be enabled (the remote-wakeup
+ setting is controlled separately by the power/wakeup
+ attribute).
+
+ During normal use, devices should be left in the "auto"
+ level. The other levels are meant for administrative uses.
+ If you want to suspend a device immediately but leave it
+ free to wake up in response to I/O requests, you should
+ write "0" to power/autosuspend.
Index: usb-2.6/drivers/usb/core/driver.c
===================================================================
--- usb-2.6.orig/drivers/usb/core/driver.c
+++ usb-2.6/drivers/usb/core/driver.c
@@ -872,8 +872,10 @@ static int usb_resume_device(struct usb_
done:
// dev_dbg(&udev->dev, "%s: status %d\n", __FUNCTION__, status);
- if (status == 0)
+ if (status == 0) {
+ udev->autoresume_disabled = 0;
udev->dev.power.power_state.event = PM_EVENT_ON;
+ }
return status;
}
@@ -970,7 +972,7 @@ static int autosuspend_check(struct usb_
udev->do_remote_wakeup = device_may_wakeup(&udev->dev);
if (udev->pm_usage_cnt > 0)
return -EBUSY;
- if (udev->autosuspend_delay < 0)
+ if (udev->autosuspend_delay < 0 || udev->autosuspend_disabled)
return -EPERM;
if (udev->actconfig) {
@@ -1116,6 +1118,8 @@ static int usb_resume_both(struct usb_de
struct usb_interface *intf;
struct usb_device *parent = udev->parent;
+ if (udev->auto_pm && udev->autoresume_disabled)
+ return -EPERM;
cancel_delayed_work(&udev->autosuspend);
if (udev->state == USB_STATE_NOTATTACHED)
return -ENODEV;
@@ -1486,9 +1490,14 @@ static int usb_suspend(struct device *de
static int usb_resume(struct device *dev)
{
+ struct usb_device *udev;
+
if (!is_usb_device(dev)) /* Ignore PM for interfaces */
return 0;
- return usb_external_resume_device(to_usb_device(dev));
+ udev = to_usb_device(dev);
+ if (udev->autoresume_disabled)
+ return -EPERM;
+ return usb_external_resume_device(udev);
}
#else
Index: usb-2.6/drivers/usb/core/sysfs.c
===================================================================
--- usb-2.6.orig/drivers/usb/core/sysfs.c
+++ usb-2.6/drivers/usb/core/sysfs.c
@@ -11,6 +11,7 @@
#include <linux/kernel.h>
+#include <linux/string.h>
#include <linux/usb.h>
#include "usb.h"
@@ -184,9 +185,8 @@ set_autosuspend(struct device *dev, stru
if (value >= 0)
usb_try_autosuspend_device(udev);
else {
- usb_lock_device(udev);
- usb_external_resume_device(udev);
- usb_unlock_device(udev);
+ if (usb_autoresume_device(udev) == 0)
+ usb_autosuspend_device(udev);
}
return count;
}
@@ -194,22 +194,95 @@ set_autosuspend(struct device *dev, stru
static DEVICE_ATTR(autosuspend, S_IRUGO | S_IWUSR,
show_autosuspend, set_autosuspend);
+static const char on_string[] = "on";
+static const char auto_string[] = "auto";
+static const char suspend_string[] = "suspend";
+
+static ssize_t
+show_level(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct usb_device *udev = to_usb_device(dev);
+ const char *p = auto_string;
+
+ if (udev->state == USB_STATE_SUSPENDED) {
+ if (udev->autoresume_disabled)
+ p = suspend_string;
+ } else {
+ if (udev->autosuspend_disabled)
+ p = on_string;
+ }
+ return sprintf(buf, "%s\n", p);
+}
+
+static ssize_t
+set_level(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct usb_device *udev = to_usb_device(dev);
+ int len = count;
+ char *cp;
+ int rc = 0;
+
+ cp = memchr(buf, '\n', count);
+ if (cp)
+ len = cp - buf;
+
+ usb_lock_device(udev);
+
+ /* Setting the flags without calling usb_pm_lock is a subject to
+ * races, but who cares...
+ */
+ if (len == sizeof on_string - 1 &&
+ strncmp(buf, on_string, len) == 0) {
+ udev->autosuspend_disabled = 1;
+ udev->autoresume_disabled = 0;
+ rc = usb_external_resume_device(udev);
+
+ } else if (len == sizeof auto_string - 1 &&
+ strncmp(buf, auto_string, len) == 0) {
+ udev->autosuspend_disabled = 0;
+ udev->autoresume_disabled = 0;
+ rc = usb_external_resume_device(udev);
+
+ } else if (len == sizeof suspend_string - 1 &&
+ strncmp(buf, suspend_string, len) == 0) {
+ udev->autosuspend_disabled = 0;
+ udev->autoresume_disabled = 1;
+ rc = usb_external_suspend_device(udev, PMSG_SUSPEND);
+
+ } else
+ rc = -EINVAL;
+
+ usb_unlock_device(udev);
+ return (rc < 0 ? rc : count);
+}
+
+static DEVICE_ATTR(level, S_IRUGO | S_IWUSR, show_level, set_level);
+
static char power_group[] = "power";
static int add_power_attributes(struct device *dev)
{
int rc = 0;
- if (is_usb_device(dev))
+ if (is_usb_device(dev)) {
rc = sysfs_add_file_to_group(&dev->kobj,
&dev_attr_autosuspend.attr,
power_group);
+ if (rc == 0)
+ rc = sysfs_add_file_to_group(&dev->kobj,
+ &dev_attr_level.attr,
+ power_group);
+ }
return rc;
}
static void remove_power_attributes(struct device *dev)
{
sysfs_remove_file_from_group(&dev->kobj,
+ &dev_attr_level.attr,
+ power_group);
+ sysfs_remove_file_from_group(&dev->kobj,
&dev_attr_autosuspend.attr,
power_group);
}
Index: usb-2.6/include/linux/usb.h
===================================================================
--- usb-2.6.orig/include/linux/usb.h
+++ usb-2.6/include/linux/usb.h
@@ -398,6 +398,8 @@ struct usb_device {
unsigned auto_pm:1; /* autosuspend/resume in progress */
unsigned do_remote_wakeup:1; /* remote wakeup should be enabled */
+ unsigned autosuspend_disabled:1; /* autosuspend and autoresume */
+ unsigned autoresume_disabled:1; /* disabled by the user */
#endif
};
#define to_usb_device(d) container_of(d, struct usb_device, dev)
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