Re: How to improve resume time of EHCI controller on Lenovo X60t?

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On Thu, 4 May 2017, Paul Menzel wrote:

> Dear Linux USB folks,
> 
> 
> With commit 85724edec (Merge tag 'leds_for_4.12' of
> git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds), 
> testing the resume time on a Lenovo X60t connected to the docking
> station with the script `analyze_suspend.py` [1][2], one USB
> controller(?) needs the most time with 376 ms.

Well, it's always going to be true that _one_ of the USB controllers
needs more time than the others.  :-)

Where do you get than 376 ms number from?  The attached graph and
listing show that 0000:00:1d.7 and usb5 (the PCI and USB interfaces of
the EHCI controller) take 18.971 ms in resume_noirq and 119.183 ms in
resume, for a total of 138.154 ms.

> > usb @ 17ef:1000 [5-6] {usb} async_device (Total Suspend: 88.202 ms Total Resume: 376.385 ms)

5-6 is not the EHCI controller.  It is a USB device plugged into that 
controller.

> Around 270 ms are spent in `generic_resume [usbcore]`.

generic_resume doesn't do anything; it just calls usb_port_resume to do
the real work.

> Please find the compressed HTML result page attached, which was created
> with `sudo ./analyze_suspend.py -config config/suspend-callgraph.cfg`.
> 
> Here is some more information about the devices.

You didn't include any information about the 5-6 device.

> Can there something be done about that?

Hard to say without knowing anything about the device.  Or what driver 
it uses.

Alan Stern

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