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

[Cho KyongHo <pullip.cho@samsung.com>]

> -----Original Message-----
> From: Antonios Motakis [mailto:a.motakis@virtualopensystems.com]
> Sent: Friday, July 19, 2013 1:25 AM
> 
> Hello Cho,
> 
> I have been trying out the Exynos System MMU driver including your
> fixes, however I notice that if you try to get the iommu_group of a
> device (i.e. iommu_group_get(&pdev->dev)) this will not work. Since
> each device is behind its own System MMU I would expect a distinct
> iommu_group for that device, instead I get NULL (I tried this with the
> MFC).
> 
> Indeed, it looks like this is not currently implemented in the driver.
> Is this something that is on the roadmap?
> 

I have not implemented anything about iommu_group
since a System MMU is dedicated to a single master device.
I also did not find any reason to implement something about iommu_group.
I would like to know why you need to call iommu_group_get().
Do you need some information in user-space?

Thank you.

Cho KyongHo.

> Best regards,
> Antonios Motakis
> 
> On Fri, Jul 5, 2013 at 2:29 PM, Cho KyongHo <pullip.cho@samsung.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.
> > For example, MFC device driver must ensure that its System MMU is disabled
> > before MFC block is power-down not to invalidate IOTLB in the System MMU
> > when I/O memory mapping is changed. Because A System MMU is resides in the
> > same H/W block, access to control registers of System MMU while the H/W
> > block is turned off must be prohibited.
> >
> > This set of changes solves the above problem with setting each System MMUs
> > as the parent of the device which owns the System MMU to recieve the
> > information when the device is turned off or turned on.
> >
> > Another big change to the driver is the support for devicetree.
> > The bindings for System MMU is described in
> > Documentation/devicetree/bindings/arm/samsung/system-mmu.txt
> >
> > In addition, this patchset also includes several bug fixes and enhancements
> > of the current driver.
> >
> > Change log:
> > v7:
> > - Rebased on the stable 3.10
> > - Registered PM domains and gate clocks with DT
> > - Changed connection method between a System MMU and its master H/W
> >    'mmu-master' property in the node of System MMU
> >    --> 'iommu' property in the node of master H/W
> > - Marking device descriptor of master H/W of a System MMU with bus notifier.
> > - Power management (PM_RUNTIME, PM_SLEEP) of System MMUs with gpd_dev_ops
> >    of Generic IO Powerdomain. gpd_dev_ops are set to the master H/Ws
> >    before they are probed in the bus notifier.
> > - Removed additional debugging features like debugfs entries and
> >    version names.
> > - Removed support for advanced features of System MMU 3.2 and 3.3
> >    the current IOMMU API cannot handle the feature
> >   (A kind of L2 TLB that fetches several consequence page table entries.
> >    It must be initialized by the driver of master H/W whenever it works.)
> >
> > v6:
> > - Rebased on the branch, next/iommu-exynos of
> >   git.kernel.org/pub/scm/linux/kernel/git/kgene/linux-samsung.git
> >
> > v5:
> > - new bugfix: patch 01
> > - Reordered patches
> >   * patch 01 ~ 05: Bugfix and enhancements of the existing driver
> >   * patch 06 ~ 10: Device Tree support and callbacks for power management
> >   * patch 11     : System MMU 3.2 and 3.3 support
> >   * patch 12 ~ 14: Debugging features
> > - Additional code compaction
> >
> > v4:
> > - Remove Change-Id from v3 patches
> > - Change the order of the third and the first patch
> >   Thanks to Kukjin Kim.
> > - Fix memory leak when allocating and assigning exynos_iommu_owner to client
> >   device if the client device has multiple System MMUs.
> >   Thanks to Rahul Sharma.
> >
> > v3:
> > - Fix prefetch buffer flag definition for System MMU 3.3 (patch 10/12)
> > - Fix incorrect setting for SET_RUNTIME_PM_OPS (patch 09/12)
> >   Thanks to Prathyush.
> >
> > v2:
> > - Split the patch to iommu/exynos into 9 patches
> > - Support for System MMU 3.3
> > - Some code compaction
> >
> > 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
> >
> > Diffstats:
> > .../devicetree/bindings/clock/exynos5250-clock.txt |   28 +-
> > .../bindings/iommu/samsung,exynos4210-sysmmu.txt   |  103 ++
> > arch/arm/boot/dts/exynos4.dtsi                     |  122 +++
> > arch/arm/boot/dts/exynos4210.dtsi                  |   25 +
> > arch/arm/boot/dts/exynos4x12.dtsi                  |   76 ++
> > arch/arm/boot/dts/exynos5250.dtsi                  |  291 ++++++
> > drivers/clk/samsung/clk-exynos5250.c               |   57 +-
> > drivers/iommu/Kconfig                              |    5 +-
> > drivers/iommu/exynos-iommu.c                       | 1011 +++++++++++++-------
> > 9 files changed, 1382 insertions(+), 336 deletions(-)
> >
> > --
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