V4L/ARM: videobuf-dma-contig no longer works on my ARM machine

Janusz Krzysztofik jkrzyszt at tis.icnet.pl
Wed Apr 13 06:20:43 EDT 2011

Dnia sobota 09 kwiecień 2011 o 18:42:40 Jiri Slaby napisał(a):
> On 04/09/2011 05:10 PM, Janusz Krzysztofik wrote:
> > (CC: Jiri Slaby, the author of the problematic change; truncate
> > subject)
> > 
> > On Sat, 09 Apr 2011, at 09:16:24, Russell King - ARM Linux wrote:
> >> On Sat, Apr 09, 2011 at 03:33:39AM +0200, Janusz Krzysztofik wrote:
> >>> Since there were no actual problems reported before, I suppose
> >>> the old code, which was passing to remap_pfn_range() a physical
> >>> page number calculated from dma_alloc_coherent() privided
> >>> dma_handle, worked correctly on all platforms actually using
> >>> videobud-dma-config.
> No, it didn't when IOMMU was used. 

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 a 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) 
uses IOMMU? If there is one, than I agree that reverting the patch is 
not a good option.

> Because remap_pfn_range didn't get
> a physical page address.

If I didn't understand it, I wouldn't try to find a solution other than 
reverting your patch.


More information about the linux-arm-kernel mailing list