linux-kernel - Re: [PATCH 5/5] thunderbolt: Add support for runtime PM

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20180708073130.GR2534@lahna.fi.intel.com>
Date:   Sun, 8 Jul 2018 10:31:30 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Lukas Wunner <lukas@...ner.de>
Cc:     linux-kernel@...r.kernel.org,
        Andreas Noever <andreas.noever@...il.com>,
        Michael Jamet <michael.jamet@...el.com>,
        Yehezkel Bernat <YehezkelShB@...il.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Christian Kellner <christian@...lner.me>,
        Mario Limonciello <mario.limonciello@...l.com>
Subject: Re: [PATCH 5/5] thunderbolt: Add support for runtime PM

On Sat, Jul 07, 2018 at 11:14:01PM +0200, Lukas Wunner wrote:
> On Mon, Jun 18, 2018 at 02:07:31PM +0300, Mika Westerberg wrote:
> > Implement this using standard Linux runtime PM APIs so that when all the
> > children devices are runtime suspended, the Thunderbolt host controller
> > PCI device is runtime suspended as well. The ICM firmware then starts
> > powering down power domains towards RTD3 but it can prevent this if it
> > detects that there is an active Display Port stream (this is not visible
> > to the software, though).
> > 
> > The Thunderbolt host controller will be runtime resumed either when
> > there is a remote wake event (device is connected or disconnected), or
> > when there is access from userspace that requires hardware access.
> 
> IIUC, if there is no xdomain, after 15 s all switch devices as well as
> the domain device and the NHI will have runtime suspended.  The control
> channel is torn down as well, so you can no longer receive notifications
> over it.  Then how is wakeup of the NHI signalled on hotplug/unplug?
> Do you get a PME for the NHI device?

Yes, it sends PME.

> Because I'm fairly certain that
> I do not get a PME for the Light Ridge in my MacBook Pro, but I'll test
> this once more and modify negotiate_os_control() to grant PME control
> to the OS.

I think in case of Apple hardware, they handle the in some different
means than PME (possibly part of chipset driver or ACPI method/event).