linux-kernel - RE: [PATCH v7 00/12] iommu/exynos: Fixes and Enhancements of System MMU driver with DT

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Date:	Mon, 15 Jul 2013 21:20:50 +0900
From:	Cho KyongHo <pullip.cho@...sung.com>
To:	'Grant Grundler' <grundler@...omium.org>
Cc:	'Linux ARM Kernel' <linux-arm-kernel@...ts.infradead.org>,
	'Linux IOMMU' <iommu@...ts.linux-foundation.org>,
	'Linux Kernel' <linux-kernel@...r.kernel.org>,
	'Linux Samsung SOC' <linux-samsung-soc@...r.kernel.org>,
	'Hyunwoong Kim' <khw0178.kim@...sung.com>,
	'Joerg Roedel' <joro@...tes.org>,
	'Kukjin Kim' <kgene.kim@...sung.com>,
	'Prathyush' <prathyush.k@...sung.com>,
	'Rahul Sharma' <rahul.sharma@...sung.com>,
	'Subash Patel' <supash.ramaswamy@...aro.org>,
	'Keyyoung Park' <keyyoung.park@...sung.com>,
	'Doug Anderson' <dianders@...omium.org>
Subject: RE: [PATCH v7 00/12] iommu/exynos: Fixes and Enhancements of System
 MMU driver with DT

> From: Cho KyongHo [mailto:pullip.cho@...sung.com]
> Sent: Monday, July 15, 2013 8:24 PM
> 
> > From: grundler@...gle.com [mailto:grundler@...gle.com] On Behalf Of Grant Grundler
> > Sent: Friday, July 12, 2013 2:23 AM
> >
> > On Fri, Jul 5, 2013 at 5:29 AM, Cho KyongHo <pullip.cho@...sung.com> wrote:
> > > The current exynos-iommu(System MMU) driver does not work autonomously
> > > since it is lack of support for power management of peripheral blocks.
> > ...
> > > Patch summary:
> > > [PATCH v7 1/9] iommu/exynos: do not include removed header
> > > [PATCH v7 2/9] iommu/exynos: add missing cache flush for removed page table entries
> > > [PATCH v7 3/9] iommu/exynos: fix page table maintenance
> > > [PATCH v7 4/9] iommu/exynos: allocate lv2 page table from own slab
> > > [PATCH v7 5/9] iommu/exynos: change rwlock to spinlock
> > > [PATCH v7 6/9] clk: exynos5250: add gate clock descriptions of System MMU
> > > [PATCH v7 7/9] ARM: dts: Add description of System MMU of Exynos SoCs
> > > [PATCH v7 8/9] iommu/exynos: support for device tree
> > > [PATCH v7 9/9] iommu/exynos: add bus notifier for registering System MMU
> >
> > Cho,
> > Of the above patches, nearly all have been applied to chromeos-3.8
> > (kernel-next git tree) by Doug Anderson and others.
> >
> > AFAICT, the only ones not applied are:
> >    [v7,3/9] iommu/exynos: fix page table maintenance
> >    [v7,6/9] clk: exynos5250: add gate clock descriptions of System MMU
> > (conflicts in this one)
> >    [v7,7/9] ARM: dts: Add description of System MMU of Exynos SoCs
> > (depends on 6/9)
> >
> > We also already have parts of:
> >    [v7,9/9] iommu/exynos: add bus notifier for registering System MMU
> >
> > Some of those are being further discussed but I've lost track now
> > exactly which ones.
> >
> > I'm telling you about chromeos-3.8 status since the adopted changes
> > have been reviewed (by me and others) are being tested manually here
> > on several different Samsung Exynos platforms (including 5250 which is
> > our "snow" platform). Not sure how you should to mark those patches
> > since they aren't identical to your changes (which apply to post 3.10
> > kernels, not 3.8).  You might consider splitting those patches out
> > from the 4 I've listed above to get that series accepted upstream
> > since the additional review/testing should provide some confidence
> > those patches are good.
> >
> 
> I understand what you are concerning about.
> Have you applied v6 patchset?
> 
> I will try to split the patches and make the changes from v6
> on top of the v6 patcheset.
> 

Actually, as you know, the previous patches include setting a System MMU
as the parent device of its master device in probe() of System MMU.
I asked Greg KH about changing device hierarchy in probe() and he answered
that it is not a good idea because it modifies sysfs even though probe() of
System MMU driver is called before sysfs is constructed.

That's why I uses genpd_pm_ops.
It results in big change in the patches after registering device tree.

I want to ask your opinion about this change :)

> > cheers,
> > grant
> 
> Thank you.
> 
> Cho KyonogHo.

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