hi alan:

2014-02-20 23:53 GMT+08:00 Alan Stern [off-list ref]:

On Thu, 20 Feb 2014, loody wrote:

quoted

hi all:

2014-01-06 23:10 GMT+08:00 Alan Stern [off-list ref]:

quoted

On Mon, 6 Jan 2014, loody wrote:

quoted

quoted

quoted

2. is it possible to change the order of calling resume callback?
    for example, suppose the original sequence is "ehci -> xhci -> tty
..." and I want to change as "tty-> ehci -> xhci".

It is possible only to a very limited extent.  You can turn async
suspend/resume on or off, and this will affect the order.  Of course,
when async suspend/resume is off, the total time required will be
longer than when it is on.

Why do you want to change the order?  It shouldn't make any difference.

Because I want the GUI and input part of driver resume as earlier as possible.
Such that user can keep on their previous work more quicker.

I doubt it will make any noticeable difference.  Remember, userspace
remains frozen until _all_ the devices have been resumed.  Until that
happens, the user can't do anything.

after tracing the kernel src, I found the usb resume call back is
called in drivers/base/power/main.c -> dpm_resume.

is that the only way usb resume functions could be called?

Yes.

I found all usb devices will be register as dev->power.async_suspend
=1 in usb_new_device.

if all usb devices' resume will be finished in
drivers/base/power/main.c -> dpm_resume, what is the difference to
register these devices as async_suspend =1?
Doesn't async_schedule in dpm_resume will let those async_suspend =1
devices resume after calling dpm_resume?

Appreciate your kind help,