[PATCH 2.6.39 v2] V4L: videobuf-dma-contig: fix mmap_mapper broken on ARM

Dnia czwartek 14 kwiecie? 2011 o 00:00:08 Russell King - ARM Linux 
napisa?(a):

On Wed, Apr 13, 2011 at 10:56:39PM +0200, Janusz Krzysztofik wrote:

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Dnia ?roda 13 kwiecie? 2011 o 20:32:31 Russell King - ARM Linux

napisa?(a):

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On Wed, Apr 13, 2011 at 12:52:31PM +0200, Janusz Krzysztofik 

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Taking into account that I'm just trying to fix a regression,
and not invent a new, long term solution: are you able to name
an ARM based board which a) is already supported in 2.6.39, b)
is (or can be) equipped with a device supported by a V4L
driver which uses videobuf- dma-config susbsystem, c) has a
bus structure with which virt_to_phys(bus_to_virt(dma_handle))
is not equal dma_handle?

I have no idea - and why should whether someone can name
something that may break be a justification to allow something
which is technically wrong?

Surely it should be the other way around - if its technically
wrong and _may_ break something then it shouldn't be allowed.

In theory - of course. In practice - couldn't we now, close to
-rc3, relax the rules a little bit and stop bothering with
something that may break in the future if it doesn't break on any
board supported so far (I hope)?

If we are worried about closeness to -final, then what should happen
is that the original commit is reverted; the "fix" for IOMMUs
resulted in a regression for existing users which isn't trivial to
resolve without risking possible breakage of other users.

Do we even know whether bus_to_virt(iommu_bus_address) works?  I
suspect it doesn't, so by doing so you're already re-breaking the
IOMMU case.

Hard to deny with only me having actually tested this dirty hack on one 
single board :)

Thanks for your support,
Janusz