Hi Marek,
On 05/03/15 14:31, Marek Szyprowski wrote:
Hello,
On 2015-01-12 21:48, Robin Murphy wrote:
Hi all,
Whilst it's a long way off perfect, this has reached the point of being
functional and stable enough to be useful, so here it is. The core
consists of the meat of the arch/arm implementation modified to remove
the assumption of PAGE_SIZE pages and ported over to the Intel IOVA
allocator instead of the bitmap-based one. For that, this series depends
on my "Genericise the IOVA allocator" series posted earlier[1].
I've tested your patches on Exynos 5433 based system and I have a few
comments. To get them working I had to do some fixes. Most of them
are already reported in this thread, the remaining I will send in a few
minutes.
Thanks!
Do you plan to send an updated patchset?
I already sent a v2 which addressed some of the major issues here:
http://thread.gmane.org/gmane.linux.kernel.iommu/8773
Following some of the feedback there I've currently got a v3 in
development, which reworks a lot of it more in favour of scatterlists,
and fills in some of the gaps needed to move arch/arm over (I still need
to look at how to handle the drivers currently making use of
dma_iommu_mapping directly).
Robin.
There are plenty of obvious things still to do, including:
* Domain and group handling is all wrong, but that's a bigger problem.
For the moment it does more or less the same thing as the arch/arm
code, which at least works for the one-IOMMU-per-device situation.
* IOMMU domains and IOVA domains probably want to be better integrated
with devices and each other, rather than having a proliferation of
arch-specific structs.
* The temporary map_sg implementation - I have a 'proper' iommu_map_sg
based one in progress, but since the simple one works it's not been
as high a priority.
Well, for ARM arch this was the main feature of IOMMU and DMA-mapping
integration. It is heavily used by some multimedia devices and dma-buf
realted stuff to get a scattered buffer mapped into contiguous IO address
space.
* Port arch/arm over to it. I'd guess it might be preferable to merge
this through arm64 first, though, rather than overcomplicate matters.
I think that the code in arch/arm is already quite well tested and can be
almost directly reused for common dma-mapping helpers.
* There may well be scope for streamlining and tidying up the copied
parts - In general I've simply avoided touching anything I don't
fully understand.
* In the same vein, I'm sure lots of it is fairly ARM-specific, so will
need longer-term work to become truly generic.
[1]:http://thread.gmane.org/gmane.linux.kernel.iommu/8208
Best regards
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