Messages in this thread | | | Date | Fri, 9 Jun 2017 10:48:41 -0400 (EDT) | From | Alan Stern <> | Subject | Re: [PATCH 0/3] USB: add API for interface driver to vote for autosuspend |
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On Thu, 8 Jun 2017, Yueyao Zhu wrote:
> From: Yueyao Zhu <yueyao@google.com> > > Currently, if a USB driver would like to enable autosuspend on the USB > device, usb_enable_autosuspend() seems to be the only option. However, > this acts on the device level, and other interfaces might not desire > to autosuspend the USB device. > > For example, for the usb digital audio driver to enable autosuspend on > a device, calling usb_enable_autosuspend() from the interface driver > might not be a good idea as the USB device might have a keyboard HID > interface which generally doesn't handle autosupend very well. > > This patch series introduces an API for interface driver to vote > for autosuspend on the interface, and when all interfaces agree to > it, autosuspend can then be enabled on the usb device.
The whole idea of this seems questionable. USB interface drivers are generally not supposed to enable or disable autosuspend -- that is a policy decision left up to userspace. There are a few exceptions for things like hubs, but this is generally true.
Why should the USB digital audio driver want to enable autosuspend?
Alan Stern
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