On Mon, 8 Jun 2009, Matthew Garrett wrote: > On Sun, Jun 07, 2009 at 11:10:52PM -0400, Alan Stern wrote: > > On Mon, 8 Jun 2009, Matthew Garrett wrote: > > > > > On Sun, Jun 07, 2009 at 11:03:48PM -0400, Alan Stern wrote: > > > > > > > There's no mechanism for this. It many environments it couldn't work, > > > > because the decision about whether to enable autosuspend is made when > > > > the device is first created (i.e., when the creation uevent is > > > > received), whereas driver binding doesn't occur until later. > > > > > > There's a lot of power management situations where you don't end up with > > > the optimal power configuration until a driver's bound. It's certainly > > > possible to do this in userspace, but if we know that the hardware > > > supported by a given driver will always work then it seems reasonable to > > > have it whitelist autosuspend on that device. > > > > Sure. Such a thing could be added easily enough. It just doesn't > > exist now, that's all. > > Something roughly like this? We'd probably also want a function call so > drivers can do it based on the ID of the device they're handling, but in > some cases we can probably assume that all devices supported by the > driver will work. My preference would be to use a function call always, rather than relying on static driver information. It provides more flexibility. > diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c > index d0a21a5..36f63a7 100644 > --- a/drivers/usb/core/driver.c > +++ b/drivers/usb/core/driver.c > @@ -355,6 +355,8 @@ int usb_driver_claim_interface(struct usb_driver *driver, > iface->condition = USB_INTERFACE_BOUND; > mark_active(iface); > iface->pm_usage_cnt = !(driver->supports_autosuspend); > + if (driver->supports_autosuspend && driver->enable_autosuspend) > + udev->autosuspend_disabled=0; Style violation: You should have blanks around the '=' sign. :-) > usb_pm_unlock(udev); That's right. If implemented as a function, turning off udev->autosuspend_disabled is all the function would need to do (provided we add the restriction that it should never be called from anywhere except inside a driver's probe routine). Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
