Re: How the EHCI HC driver make the decision to suspend some USB devices?

From	Alan Stern <stern@rowland.harvard.edu>
Newsgroups	linux.kernel
Subject	Re: How the EHCI HC driver make the decision to suspend some USB devices?
Date	2016-08-19 16:20 +0200
Message-ID	<s7SOm-6FX-19@gated-at.bofh.it> (permalink)
References	<s7SOm-6FX-21@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Fri, 19 Aug 2016, ludeng wrote:

> Hi,
> How the EHCI HC driver make the decision to suspend some USB devices,
> but not to suspend some others? We notice that for some USB Video
> Cameras, when they are enumerated and there is no data to transfer,
> the EHCI HC driver will suspend them by setting the Suspend bit of
> the PORTSC register. But for some other Cameras, the EHCI HC driver
> will not suspend them. The drvier make the decision based on what
> kind of information of the device ?

The EHCI driver does not make this decision.  The decision is made by 
the video camera driver and by the user.

Alan Stern

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

Re: How the EHCI HC driver make the decision to suspend some USB  devices? Alan Stern <stern@rowland.harvard.edu> - 2016-08-19 16:20 +0200
  Re: How the EHCI HC driver make the decision to suspend some USB  devices? Oliver Neukum <oneukum@suse.com> - 2016-08-22 11:10 +0200

csiph-web