linux-kernel - [PATCH v5 0/7] Exynos IOMMU: proper runtime PM support (use device dependencies)

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Message-id: <1476948173-21093-1-git-send-email-m.szyprowski@samsung.com>
Date:   Thu, 20 Oct 2016 09:22:46 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-samsung-soc@...r.kernel.org
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Joerg Roedel <joro@...tes.org>,
        Inki Dae <inki.dae@...sung.com>, Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Mark Brown <broonie@...nel.org>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Lukas Wunner <lukas@...ner.de>,
        Kevin Hilman <khilman@...nel.org>,
        Tobias Jakobi <tjakobi@...h.uni-bielefeld.de>,
        Tomasz Figa <tomasz.figa@...il.com>
Subject: [PATCH v5 0/7] Exynos IOMMU: proper runtime PM support (use device
 dependencies)

Hello,

This is another update of the patchset for adding proper runtime PM
support to Exynos IOMMU driver. This has been achieved by using recently
introduced device links, which lets SYSMMU controller's runtime PM to
follow master's device runtime PM state (the device which actually
performs DMA transaction). The main idea behind this solution is an
observation that any DMA activity from master device can be done only
when master device is active, thus when master device is suspended
SYSMMU controller device can also be suspended.

This patchset solves the problem of all power domains being always
enabled. It happened, because all SYSMMU controllers (which belongs to
the same domains) are permanently kept active, because existing driver
was simplified and kept SYSMMU device active all the time after
initialization and attaching to the master device.

Patch requires fifth version of Rafeal's "Functional dependencies
between devices" patchset, which is available here:
http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1246897.html
or as git branch:
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git device-links-test

If one wants to test this patchset, I've provided a branch with all needed
patches (a small fix for Exynos4 FIMC-IS DTS is still needed):
https://git.linaro.org/people/marek.szyprowski/linux-srpol.git v4.9-iommu-pm-v5

Patches are based on vanilla v4.9-rc1 kernel with Rafael's device
dependencies v5 patchset applied.

Best regards
Marek Szyprowski
Samsung R&D Institute Poland


Changelog:
v5:
- split main patch into several small changes for easier review (requested
  by Luis Rodriquez)
- fixed usage of runtime_pm_active, now it is guarded by pm_runtime_get_noresume()
  and pm_runtime_put() pair

v4: http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1241601.html
- rebased on top of v4 of device dependencies/links patchset, what resolved
  system hang on reboot

v3: http://www.spinics.net/lists/linux-samsung-soc/msg55256.html
- rebased on top of latest device dependencies/links patchset
- added proper locking between runtime pm, iommu_attach/detach and sysmmu
  enable/disable(added per iommu owner device's rpm lock)

v2: http://www.spinics.net/lists/arm-kernel/msg512082.html
- replaced PM notifiers with generic device dependencies/links developed
  by Rafael J. Wysocki

v1: http://www.spinics.net/lists/arm-kernel/msg509600.html
- initial version


Patch summary:

Marek Szyprowski (7):
  iommu/exynos: Remove excessive, useless debug
  iommu/exynos: Remove dead code
  iommu/exynos: Simplify internal enable/disable functions
  iommu/exynos: Set master device once on boot
  iommu/exynos: Rework and fix internal locking
  iommu/exynos: Add runtime pm support
  iommu/exynos: Use device dependency links to control runtime pm

 drivers/iommu/exynos-iommu.c | 230 ++++++++++++++++++-------------------------
 1 file changed, 95 insertions(+), 135 deletions(-)

-- 
1.9.1