On Thu, Aug 26, 2010 at 06:51:48PM +0900, FUJITA Tomonori wrote: > On Thu, 26 Aug 2010 11:45:58 +0200 (CEST) > Guennadi Liakhovetski <g.liakhovetski@xxxxxx> wrote: > > > On Thu, 26 Aug 2010, FUJITA Tomonori wrote: > > > > > Why can't you revert a commit that causes the regression? > > > > See this reply, and the complete thread too. > > > > http://marc.info/?l=linux-sh&m=128130485208262&w=2 > > > > > The related DMA API wasn't changed in 2.6.36-rc1. The DMA API is not > > > responsible for the regression. And the patchset even exnteds the > > > definition of the DMA API (dma_declare_coherent_memory). Such change > > > shouldn't applied after rc1. I think that DMA-API.txt says that > > > dma_declare_coherent_memory() handles coherent memory for a particular > > > device. It's not for the API that reserves coherent memory that can be > > > used for any device for a single device. > > > > Anyway, we need a way to fix the regression. > > Needs to find a different way. No. ioremap on memory mapped by the kernel is just plain not permitted with ARMv6 and ARMv7 architectures. It's not something you can say "oh, need to find another way" because there is _no_ software solution to having physical regions mapped multiple times with different attributes. It's an architectural restriction. We can't unmap the kernel's memory mapping either, as I've already explained several times this month - and I'm getting frustrated at having to keep on explaining that point. Just accept the plain fact that multiple mappings of the same physical regions have become illegal. What we need is another alternative other than using ioremap on memory already mapped by the kernel - eg, by reserving a certain chunk of memory for this purpose at boot time which his _never_ mapped by the kernel, except via ioremap. -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
