From: "Luis R. Rodriguez" <mcgrof@kernel.org>
To: Lukas Wunner <lukas@wunner.de>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Linux PM list <linux-pm@vger.kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Alan Stern <stern@rowland.harvard.edu>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Tomeu Vizoso <tomeu.vizoso@collabora.com>,
Mark Brown <broonie@kernel.org>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Kevin Hilman <khilman@kernel.org>,
Ulf Hansson <ulf.hansson@linaro.org>,
Grant Likely <grant.likely@secretlab.ca>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Lars-Peter Clausen <lars@metafoo.de>,
Andrzej Hajda <a.hajda@samsung.com>
Subject: Re: [PATCH v5 2/5] driver core: Functional dependencies tracking support
Date: Mon, 14 Nov 2016 14:48:32 +0100 [thread overview]
Message-ID: <20161114134831.GX13978@wotan.suse.de> (raw)
In-Reply-To: <20161113173413.GB9598@wunner.de>
On Sun, Nov 13, 2016 at 06:34:13PM +0100, Lukas Wunner wrote:
> On Mon, Nov 07, 2016 at 10:39:54PM +0100, Luis R. Rodriguez wrote:
> > On Mon, Oct 10, 2016 at 02:51:04PM +0200, Rafael J. Wysocki wrote:
> > > One of the actions carried out by device_link_add() is to reorder
> > > the lists used for device shutdown and system suspend/resume to
> > > put the consumer device along with all of its children and all of
> > > its consumers (and so on, recursively) to the ends of those lists
> > > in order to ensure the right ordering between all of the supplier
> > > and consumer devices.
> >
> > There's no explanation as to why this order is ensured to be
> > correct, I think its important to document this. From our discussions
> > at Plumbers it seems the order is ensured due to the fact that order
> > was already implicitly provided through platform firmware (ACPI
> > enumeration is one), adjusting order on the dpm list is just shuffling
> > order between consumer / provider, but nothing else.
>
> ACPI specifies a hierarchy and the order on the dpm_list and
> devices_kset is such that children are behind their parent.
>
> A device link specifies a dependency that exists in addition
> to the hierarchy, hence consumers need to be moved behind
> their supplier. And not only the consumers themselves but
> also recursively their children and consumers. Essentially
> the entire subtree is moved to the back. That happens in
> device_reorder_to_tail() in patch 2.
Ah neat, I failed to notice this full subtree tree move, its
rather important.
> If another device is enumerated which acts as a supplier to
> an existing other supplier, that other supplier and all its
> dependents are moved behind the newly enumerated device,
> and so on.
>
> That is probably correct so long as no loops are introduced
> in the dependency graph.
"Probably" is what concerns me, there is no formality about
the correctness of this.
> That is checked by device_is_dependent(),
> which is called from device_link_add(), and the addition of the
> link is aborted if a loop is detected.
And that is sufficient ?
Luis
next prev parent reply other threads:[~2016-11-14 13:48 UTC|newest]
Thread overview: 138+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-08 21:25 [RFC/RFT][PATCH v2 0/7] Functional dependencies between devices Rafael J. Wysocki
2016-09-08 21:26 ` [RFC/RFT][PATCH v2 1/7] driver core: Add a wrapper around __device_release_driver() Rafael J. Wysocki
2016-09-08 21:27 ` [RFC/RFT][PATCH v2 2/7] driver core: Functional dependencies tracking support Rafael J. Wysocki
2016-09-09 8:25 ` Ulf Hansson
2016-09-09 12:06 ` Mark Brown
2016-09-09 14:13 ` Ulf Hansson
2016-09-15 1:11 ` Rafael J. Wysocki
2016-09-11 13:40 ` Lukas Wunner
2016-09-11 20:43 ` Lukas Wunner
2016-09-14 1:21 ` Rafael J. Wysocki
2016-09-14 8:28 ` Lukas Wunner
2016-09-14 13:17 ` Rafael J. Wysocki
2016-09-08 21:28 ` [RFC/RFT][PATCH v2 3/7] PM / sleep: Make async suspend/resume of devices use device links Rafael J. Wysocki
2016-09-10 13:31 ` Lukas Wunner
2016-09-10 22:12 ` Rafael J. Wysocki
2016-09-08 21:29 ` [RFC/RFT][PATCH v2 4/7] PM / runtime: Pass flags argument to __pm_runtime_disable() Rafael J. Wysocki
2016-09-08 21:29 ` [RFC/RFT][PATCH v2 5/7] PM / runtime: Flag to indicate PM sleep transitions in progress Rafael J. Wysocki
2016-09-12 14:07 ` Lukas Wunner
2016-09-12 21:25 ` Rafael J. Wysocki
2016-09-12 22:52 ` Lukas Wunner
2016-09-13 7:21 ` Marek Szyprowski
2016-09-13 23:59 ` Rafael J. Wysocki
2016-09-08 21:30 ` [RFC/RFT][PATCH v2 6/7] PM / runtime: Use device links Rafael J. Wysocki
2016-09-12 9:47 ` Lukas Wunner
2016-09-12 13:57 ` Rafael J. Wysocki
2016-09-14 1:19 ` Rafael J. Wysocki
2016-09-08 21:31 ` [RFC/RFT][PATCH v2 7/7] PM / runtime: Optimize the use of " Rafael J. Wysocki
2016-09-08 21:35 ` [RFC/RFT][PATCH v2 0/7] Functional dependencies between devices Rafael J. Wysocki
2016-09-10 11:39 ` Lukas Wunner
2016-09-10 22:04 ` Rafael J. Wysocki
2016-09-13 17:57 ` Lukas Wunner
2016-09-13 23:18 ` Rafael J. Wysocki
2016-09-18 12:39 ` Lukas Wunner
[not found] ` <CGME20160913095858eucas1p267ec2397c9e4577f94557e4a38498164@eucas1p2.samsung.com>
2016-09-13 9:58 ` Marek Szyprowski
2016-09-13 22:41 ` Rafael J. Wysocki
2016-09-18 11:23 ` Lukas Wunner
2016-09-15 22:03 ` [RFC/RFT][PATCH v3 0/5] " Rafael J. Wysocki
2016-09-15 22:04 ` [Resend][RFC/RFT][PATCH v3 1/5] driver core: Add a wrapper around __device_release_driver() Rafael J. Wysocki
2016-09-15 22:06 ` [RFC/RFT][PATCH v3 2/5] driver core: Functional dependencies tracking support Rafael J. Wysocki
2016-09-16 7:53 ` Marek Szyprowski
2016-09-16 12:06 ` Rafael J. Wysocki
2016-09-16 12:33 ` [Update][RFC/RFT][PATCH " Rafael J. Wysocki
2016-09-19 22:46 ` Lukas Wunner
2016-09-23 13:03 ` Lukas Wunner
2016-09-23 13:42 ` Rafael J. Wysocki
2016-09-26 16:51 ` Lukas Wunner
2016-09-27 12:16 ` Rafael J. Wysocki
2016-09-27 8:54 ` Lukas Wunner
2016-09-27 11:52 ` Rafael J. Wysocki
2016-09-28 10:43 ` Lukas Wunner
2016-09-28 11:31 ` Rafael J. Wysocki
2016-09-29 10:36 ` Lukas Wunner
2016-09-15 22:06 ` [RFC/RFT][PATCH v3 3/5] PM / sleep: Make async suspend/resume of devices use device links Rafael J. Wysocki
2016-09-15 22:07 ` [RFC/RFT][PATCH v3 4/5] PM / runtime: Use " Rafael J. Wysocki
2016-09-15 22:07 ` [RFC/RFT][PATCH v3 5/5] PM / runtime: Optimize the use of " Rafael J. Wysocki
2016-09-16 7:25 ` [RFC/RFT][PATCH v3 0/5] Functional dependencies between devices Marek Szyprowski
2016-09-16 7:57 ` Marek Szyprowski
2016-09-16 12:04 ` Rafael J. Wysocki
2016-09-27 12:34 ` Lukas Wunner
2016-09-28 0:33 ` Rafael J. Wysocki
2016-09-28 11:42 ` Lukas Wunner
2016-09-29 0:51 ` Rafael J. Wysocki
2016-11-15 18:50 ` Lukas Wunner
2016-09-29 0:24 ` [PATCH v4 " Rafael J. Wysocki
2016-09-29 0:25 ` [Resend][PATCH v4 1/5] driver core: Add a wrapper around __device_release_driver() Rafael J. Wysocki
2016-09-29 0:38 ` [PATCH v4 2/5] driver core: Functional dependencies tracking support Rafael J. Wysocki
2016-10-01 7:43 ` Lukas Wunner
2016-10-01 23:32 ` Rafael J. Wysocki
2016-09-29 0:38 ` [Resend][PATCH v4 3/5] PM / sleep: Make async suspend/resume of devices use device links Rafael J. Wysocki
2016-09-29 0:40 ` [PATCH v4 4/5] PM / runtime: Use " Rafael J. Wysocki
2016-09-29 0:41 ` [Rebase][PATCH v4 5/5] PM / runtime: Optimize the use of " Rafael J. Wysocki
2016-09-29 6:58 ` [PATCH v4 0/5] Functional dependencies between devices Marek Szyprowski
2016-09-29 12:27 ` Rafael J. Wysocki
2016-10-02 23:13 ` Lukas Wunner
2016-10-10 12:36 ` [PATCH v5 " Rafael J. Wysocki
2016-10-10 12:37 ` [Resend][PATCH v5 1/5] driver core: Add a wrapper around __device_release_driver() Rafael J. Wysocki
2016-10-10 12:51 ` [PATCH v5 2/5] driver core: Functional dependencies tracking support Rafael J. Wysocki
2016-10-26 11:19 ` Lukas Wunner
2016-10-27 15:25 ` Greg Kroah-Hartman
2016-10-28 9:57 ` Lukas Wunner
2016-11-07 21:22 ` Luis R. Rodriguez
2016-11-08 6:45 ` Greg Kroah-Hartman
2016-11-08 19:21 ` Luis R. Rodriguez
2016-11-08 19:43 ` Greg Kroah-Hartman
2016-11-08 20:58 ` Luis R. Rodriguez
2016-11-09 6:45 ` Greg Kroah-Hartman
2016-11-09 9:36 ` Andrzej Hajda
2016-11-09 9:41 ` Greg Kroah-Hartman
2016-11-13 16:58 ` Lukas Wunner
2016-11-10 0:43 ` Rafael J. Wysocki
2016-11-10 0:59 ` Luis R. Rodriguez
2016-11-10 7:14 ` Laurent Pinchart
2016-11-10 22:04 ` Luis R. Rodriguez
2016-11-10 22:40 ` Greg Kroah-Hartman
2016-11-11 0:08 ` Laurent Pinchart
2016-11-13 10:59 ` Greg Kroah-Hartman
2016-11-14 14:50 ` Luis R. Rodriguez
2016-11-14 8:15 ` Geert Uytterhoeven
2016-11-10 8:46 ` Geert Uytterhoeven
2016-11-10 22:12 ` Luis R. Rodriguez
2016-10-27 15:32 ` Greg Kroah-Hartman
2016-11-07 21:39 ` Luis R. Rodriguez
2016-11-10 1:07 ` Rafael J. Wysocki
2016-11-10 7:05 ` Laurent Pinchart
2016-11-10 23:09 ` Luis R. Rodriguez
2016-11-13 17:34 ` Lukas Wunner
2016-11-14 13:48 ` Luis R. Rodriguez [this message]
2016-11-14 15:48 ` Lukas Wunner
2016-11-14 16:00 ` Luis R. Rodriguez
2016-10-10 12:54 ` [PATCH v5 3/5] PM / sleep: Make async suspend/resume of devices use device links Rafael J. Wysocki
2016-10-10 12:56 ` [PATCH v5 4/5] PM / runtime: Use " Rafael J. Wysocki
2016-10-20 13:17 ` [Update][PATCH " Rafael J. Wysocki
2016-10-10 12:57 ` [Rebase][PATCH v5 5/5] PM / runtime: Optimize the use of " Rafael J. Wysocki
2016-10-18 10:46 ` [PATCH v5 0/5] Functional dependencies between devices Marek Szyprowski
2016-10-19 11:57 ` Rafael J. Wysocki
2016-10-20 10:21 ` Marek Szyprowski
2016-10-20 12:54 ` Rafael J. Wysocki
2016-10-27 15:32 ` Greg Kroah-Hartman
[not found] ` <5811F0CF.5000204@huawei.com>
2016-10-28 9:39 ` Lukas Wunner
2016-11-02 20:55 ` Hanjun Guo
2016-10-30 16:22 ` [PATCH v6 " Rafael J. Wysocki
2016-10-30 16:28 ` [Resend][PATCH v6 3/5] PM / sleep: Make async suspend/resume of devices use device links Rafael J. Wysocki
2016-10-30 16:29 ` [Resend][PATCH v6 1/5] driver core: Add a wrapper around __device_release_driver() Rafael J. Wysocki
2016-10-30 16:32 ` [PATCH v6 2/5] driver core: Functional dependencies tracking support Rafael J. Wysocki
2016-10-30 16:32 ` [PATCH v6 4/5] PM / runtime: Use device links Rafael J. Wysocki
2016-12-18 14:01 ` Lukas Wunner
2016-12-18 15:53 ` Rafael J. Wysocki
2016-12-18 16:37 ` Lukas Wunner
2016-12-19 12:38 ` Rafael J. Wysocki
2016-10-30 16:32 ` [Resend][PATCH v6 5/5] PM / runtime: Optimize the use of " Rafael J. Wysocki
2016-10-30 16:40 ` [PATCH v6 0/5] Functional dependencies between devices Rafael J. Wysocki
2016-10-31 17:47 ` Greg Kroah-Hartman
2016-11-01 3:50 ` Rafael J. Wysocki
2016-11-02 7:58 ` Marek Szyprowski
2016-11-05 12:10 ` Greg Kroah-Hartman
2016-11-07 21:15 ` Luis R. Rodriguez
2016-11-08 6:36 ` Marek Szyprowski
2016-11-08 20:14 ` Luis R. Rodriguez
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