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Date:   Tue, 19 Apr 2022 17:51:38 +0200
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Subject: Re: [PATCH v2 0/2] USB: Quiesce interrupts across pm freeze
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To:     Alan Stern <stern@rowland.harvard.edu>,
        Oliver Neukum <oneukum@suse.com>
CC:     Evan Green <evgreen@chromium.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Mathias Nyman <mathias.nyman@intel.com>,
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        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        Razvan Heghedus <heghedus.razvan@gmail.com>,
        Wei Ming Chen <jj251510319013@gmail.com>,
        Youngjin Jang <yj84.jang@samsung.com>,
        linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org
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From:   Oliver Neukum <oneukum@suse.com>
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On 19.04.22 16:35, Alan Stern wrote:
> On Tue, Apr 19, 2022 at 09:05:53AM +0200, Oliver Neukum wrote:
>
>
> We have a set of quirky devices that need HID_QUIRK_ALWAYS_POLL.
> They have the nasty firmware bug that, if you suspend them without
> remote wakeup, they will crash or reset themselves.
> I am afraid that has an obvious relevance to your cool patches.
> I am not completely sure how to deal with this. It seems to me that the
> quirk will need to be shifted from HID to core USB and thaw() needs to
> be translated into usb_device_reset() + reset_resume() for them,
> but I am not really sure about the optimal mechanism.
> We may not need to do anything.  This patch specifically addresses=20
> hibernation, not system suspend or runtime suspend.  A device crashing=20
> or resetting during hibernation is not at all unusual; we should be able=
=20
> to handle such cases properly.
>
> The THAW part of suspend-to-hibernation is used only for writing the=20
> memory image to permanent storage.  I doubt that a malfunctioning HID=20
> device would interfere with this process.
>
True, if and only if all goes well. At the time thaw() has run writing
the image to disk can still fail. In that case the devices will still
be needed.

=C2=A0=C2=A0=C2=A0 Regards
=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 Oliver