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From:   Chris Chiu <chris.chiu@canonical.com>
Date:   Tue, 20 Apr 2021 15:14:56 +0800
Message-ID: <CABTNMG0hnfXH8yqd6Zbk3EiZtg4JUpJomn180NHUyAdgZjL7pA@mail.gmail.com>
Subject: Re: [PATCH v3] USB: Don't set USB_PORT_FEAT_SUSPEND on WD19's Realtek Hub
To:     Alan Stern <stern@rowland.harvard.edu>
Cc:     Greg KH <gregkh@linuxfoundation.org>, m.v.b@runbox.com,
        hadess@hadess.net, linux-usb@vger.kernel.org,
        Linux Kernel <linux-kernel@vger.kernel.org>
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On Mon, Apr 19, 2021 at 10:19 PM Alan Stern <stern@rowland.harvard.edu> wrote:
>
> On Mon, Apr 19, 2021 at 01:11:38AM -0400, Chris Chiu wrote:
> > Sorry that I didn't make myself clear. I found that if I applied RESET_RESUME
> > quirk on the problematic hub, the Set-Port-Feature(suspend) timeout error
> > disappeared. SInce the timeout is not happening for each suspend by default,
> > I suspect maybe reset-resume take everything back to clean state for the hub
> > and the Set-Port-Feature(suspend) can be taken care of w/o problems.
>
> Okay, that's a good solution for system suspend.
>
> > I didn't like RESET_RESUME because runtime PM would not work on the quirked
> > device.
>
> A more interesting question is whether it will work for devices plugged
> into the hub.  Even though the hub won't be runtime suspended, the
> things attached to it might be.
>
> >  But if the Set-Port-Feature(suspend) can't be handled and
> > skipped, I can't
> > expect the runtime PM to work for all devices connected to the hub either.
> > Is that right? If what I proposed in the patch can not get better
> > result than existing
> > quirk, I think using the RESET_RESUME would be a better option. Any suggestions?
>
> Try the RESET_RESUME quirk and see how well it works with runtime
> suspend.
>
> Alan Stern

[  453.064346] usb 3-4: finish reset-resume
[  453.192387] usb 3-4: reset high-speed USB device number 2 using xhci_hcd
[  453.339916] usb 3-4: USB quirks for this device: 2

Seems that even w/ the RESET_RESUME enabled, the connected device still
can runtime suspend/resume. That's acceptable to me. I'll send the patch
with the reset-resume quirk later.

[  626.081068] usb 3-4.3.1: usb auto-suspend, wakeup 0
[  632.552071] usb 3-4.3.1: usb auto-resume
[  632.617467] usb 3-4.3.1: Waited 0ms for CONNECT
[  632.617471] usb 3-4.3.1: finish resume

Chris