linux-kernel - Re: [PATCH v2 00/10] Exynos IOMMU: proper runtime PM support (use device dependencies)

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Date:	Fri, 15 Jul 2016 15:21:22 +0200
From:	Tobias Jakobi <tjakobi@...h.uni-bielefeld.de>
To:	Tobias Jakobi <tjakobi@...h.uni-bielefeld.de>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	iommu@...ts.linux-foundation.org,
	linux-samsung-soc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Cc:	Joerg Roedel <joro@...tes.org>, Inki Dae <inki.dae@...sung.com>,
	Kukjin Kim <kgene@...nel.org>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Mark Brown <broonie@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v2 00/10] Exynos IOMMU: proper runtime PM support (use
 device dependencies)

Tobias Jakobi wrote:
> Hello Marek,
> 
> I've tested the patchset on 4.7-rc7 and noticed that it breaks reboot on
> my ODROID-X2.
> 
> Going to check where exactly things break.
Sadly it's the last patch where everything comes together:
"iommu/exynos: Add proper runtime pm support"

I still have to check if forcing runpm status to 'on' makes a
difference. I suspect that the aggressive clock gating might be the reason?

With best wishes,
Tobias

> With best wishes,
> Tobias
> 
> 
> Marek Szyprowski wrote:
>> Hello,
>>
>> This patch series finally implements proper runtime PM support in Exynos
>> IOMMU driver. This has been achieved by using device links, which lets
>> SYSMMU controller's runtime PM to follow master's device runtime PM (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 situation that power domains are always enabled,
>> because all SYSMMU controllers (which belongs to those domains) are
>> permanently active (because existing driver was simplified and kept
>> SYSMMU device active all the time after initialization).
>>
>> Patches 1-5 are resend of the "[RFC][PATCH 0/5] Functional dependencies
>> between devices" patchset:
>> http://thread.gmane.org/gmane.linux.power-management.general/67424/focus=2126379
>> I've included them here, because it is hard to find them all on mailing
>> list archives.
>>
>> Patches 6-8 are fixes to device dependencies/links code, which were
>> required to use this solution for Exynos IOMMU driver. I'm not PM/runtime
>> PM code expert, so please double check if my changes are really correct.
>>
>> This patchset requires my previous changes to Exynos IOMMU driver
>> submitted in the "Exynos IOMMU: improve clock management" thread:
>> http://www.spinics.net/lists/arm-kernel/msg505695.html
>>
>> Best regards
>> Marek Szyprowski
>> Samsung R&D Institute Poland
>>
>>
>> Changelog:
>> v2:
>> - replaced PM notifiers with generic device dependencies/links developped
>>   by Rafael J. Wysocki
>>
>> v1: http://www.spinics.net/lists/arm-kernel/msg509600.html
>> - initial version
>>
>>
>> Patch summary:
>>
>> Marek Szyprowski (5):
>>   driver core: Avoid endless recursion if device has more than one link
>>   driver core: Add support for links to already probed drivers
>>   PM core: Fix restoring devices with links during system PM transition
>>   iommu/exynos: Remove excessive, useless debug
>>   iommu/exynos: Add proper runtime pm support
>>
>> Rafael J. Wysocki (5):
>>   driver core: Add a wrapper around __device_release_driver()
>>   driver core: Functional dependencies tracking support
>>   PM core: Make async suspend/resume of devices use device links
>>   PM core: Make runtime PM of devices use device links
>>   PM core: Optimize the use of device links for runtime PM
>>
>>  drivers/base/base.h          |  13 ++
>>  drivers/base/core.c          | 410 +++++++++++++++++++++++++++++++++++++++++++
>>  drivers/base/dd.c            |  65 +++++--
>>  drivers/base/power/main.c    |  68 ++++++-
>>  drivers/base/power/runtime.c | 130 +++++++++++++-
>>  drivers/iommu/exynos-iommu.c | 221 +++++++++++------------
>>  include/linux/device.h       |  41 +++++
>>  include/linux/pm.h           |   1 +
>>  include/linux/pm_runtime.h   |   6 +
>>  9 files changed, 809 insertions(+), 146 deletions(-)
>>
> 
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