On Mon, 7 Dec 2015, Felipe Balbi wrote:
> if those are not enabled, then the device doesn't have pm_runtime
> callbacks, see:
>
> int dpm_sysfs_add(struct device *dev)
> {
> int rc;
>
> rc = sysfs_create_group(&dev->kobj, &pm_attr_group);
> if (rc)
> return rc;
>
> if (pm_runtime_callbacks_present(dev)) {
> rc = sysfs_merge_group(&dev->kobj, &pm_runtime_attr_group);
> if (rc)
> goto err_out;
> }
> if (device_can_wakeup(dev)) {
> rc = sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
> if (rc)
> goto err_runtime;
> }
> if (dev->power.set_latency_tolerance) {
> rc = sysfs_merge_group(&dev->kobj,
> &pm_qos_latency_tolerance_attr_group);
> if (rc)
> goto err_wakeup;
> }
> return 0;
>
> err_wakeup:
> sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
> err_runtime:
> sysfs_unmerge_group(&dev->kobj, &pm_runtime_attr_group);
> err_out:
> sysfs_remove_group(&dev->kobj, &pm_attr_group);
> return rc;
> }
>
> It seems like usbcore always calls pm_runtime_no_callbacks() (which
> makes pm_runtime_callbacks_present() above fail) for all interfaces, but
> I can't seem to find where that's undone. Alan, any hints ?
The USB subsystem treats runtime PM of interfaces differently from
runtime PM of devices. Josh should be monitoring the device, not the
interface.
Alan Stern
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