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| author | Alan Stern <stern@rowland.harvard.edu> | 2010-01-08 20:57:02 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-03-03 01:54:11 +0300 |
| commit | 5899f1e020c8d53b2b6fbd6a6cf39c891ccdfade (patch) | |
| tree | acd9041996aa81db4bdc9a30fe1926e511d7eb77 /drivers/usb/core/sysfs.c | |
| parent | 088f7fec8a0e683db72fd8826c5d3ab914e197b1 (diff) | |
| download | linux-5899f1e020c8d53b2b6fbd6a6cf39c891ccdfade.tar.xz | |
USB: change handling of negative autosuspend delays
This patch (as1327) changes the way negative autosuspend delays
prevent device from autosuspending. The current code checks for
negative values explicitly in the autosuspend_check() routine. The
updated code keeps things from getting that far by using
usb_autoresume_device() to increment the usage counter when a negative
delay is set, and by using usb_autosuspend_device() to decrement the
usage counter when a non-negative delay is set.
This complicates the set_autosuspend() attribute method code slightly,
but it will reduce the overall power management overhead.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/core/sysfs.c')
| -rw-r--r-- | drivers/usb/core/sysfs.c | 22 |
1 files changed, 17 insertions, 5 deletions
diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c index 313e241f5ccc..43c002e3a9aa 100644 --- a/drivers/usb/core/sysfs.c +++ b/drivers/usb/core/sysfs.c @@ -346,7 +346,8 @@ set_autosuspend(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { struct usb_device *udev = to_usb_device(dev); - int value; + int value, old_delay; + int rc; if (sscanf(buf, "%d", &value) != 1 || value >= INT_MAX/HZ || value <= - INT_MAX/HZ) @@ -354,13 +355,24 @@ set_autosuspend(struct device *dev, struct device_attribute *attr, value *= HZ; usb_lock_device(udev); + old_delay = udev->autosuspend_delay; udev->autosuspend_delay = value; - if (value >= 0) - usb_try_autosuspend_device(udev); - else { - if (usb_autoresume_device(udev) == 0) + + if (old_delay < 0) { /* Autosuspend wasn't allowed */ + if (value >= 0) usb_autosuspend_device(udev); + } else { /* Autosuspend was allowed */ + if (value < 0) { + rc = usb_autoresume_device(udev); + if (rc < 0) { + count = rc; + udev->autosuspend_delay = old_delay; + } + } else { + usb_try_autosuspend_device(udev); + } } + usb_unlock_device(udev); return count; } |