On Thu, 18 Jan 2007, Oliver Neukum wrote:
> Hi,
>
> this patch introduces a new attribute for USB devices named "autosuspend".
> It can be used to block autosuspend for each device individually. 0 means
> disallow suspending; 1 means allow suspending.
>
> This is needed for devices which recharge their batteries of the bus.
> It compiles and is tested. For devices which crash when suspended it
> is not usefull unfortunately. This has been tested, too :-(
Are you sure the patch passed testing? See below...
> --- a/drivers/usb/core/sysfs.c 2007-01-18 13:13:35.000000000 +0100
> +++ b/drivers/usb/core/sysfs.c 2007-01-18 13:24:50.000000000 +0100
> @@ -148,6 +148,44 @@
> }
> static DEVICE_ATTR(maxchild, S_IRUGO, show_maxchild, NULL);
>
> +static ssize_t
> +show_autosuspend (struct device *dev, struct device_attribute *attr, char
> *buf)
The current convention is that we will not put a blank between the
function name and the following open paren in new code. Old code can be
cleaned up whenever someone feels like doing it (i.e., probably not for a
long time).
> +{
> + int autosusp;
> + struct usb_device *udev;
> +
> + udev = to_usb_device (dev);
> + usb_lock_device (udev);
> + autosusp = udev->can_autosuspend;
> + usb_unlock_device (udev);
> + return sprintf (buf, "%d\n", autosusp);
> +}
You don't really need to lock the device here, although it doesn't hurt.
> @@ -234,12 +272,16 @@
> if (retval)
> goto error;
> }
> + retval = device_create_file(dev, &dev_attr_autosuspend);
> + if (retval)
> + goto error;
> retval = usb_create_ep_files(dev, &udev->ep0, udev);
> if (retval)
> goto error;
> return 0;
> error:
> usb_remove_ep_files(&udev->ep0);
> + device_remove_file(dev, &dev_attr_autosuspend);
> device_remove_file(dev, &dev_attr_manufacturer);
> device_remove_file(dev, &dev_attr_product);
> device_remove_file(dev, &dev_attr_serial);
This isn't necessary. Simply add &dev_attr_autosuspend.attr to the end of
the dev_attrs array.
> --- a/drivers/usb/core/driver.c 2007-01-18 13:13:22.000000000 +0100
> +++ b/drivers/usb/core/driver.c 2007-01-18 13:02:46.000000000 +0100
> @@ -948,7 +948,8 @@
> int i;
> struct usb_interface *intf;
>
> - /* For autosuspend, fail fast if anything is in use.
> + /* For autosuspend, fail fast if anything is in use or autosuspend
> + * is disabled through sysfs.
> * Also fail if any interfaces require remote wakeup but it
> * isn't available. */
> udev->do_remote_wakeup = device_may_wakeup(&udev->dev);
What happened to the code that actually checks the flag?
Alan Stern
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