> The problem now is that that PCI register space gets mapped with
> caching enabled (by looking at the TLB contents), so I still can't
> control the device. I did some search and indeed UIO device driver
> came up, I'll read the article. I was wondering though if there is a
> simpler way to modify cache attributes of a region. mmap() doesn't
> seem to provide an interface for that, is there some other function to
> call to configure 'cache inhibit' attribute for a region?
The issue would be related to phys_mem_access_prot() not doing the right
thing in this case. In fact it looks like the arch/powerpc
page_is_ram() implementation has the same bug that I fixed a long time
ago for arch/ppc in 8b150478 ("[PATCH] ppc: make phys_mem_access_prot()
work with pfns instead of addresses"). I'll send a patch a little later
that you can try out.
- R.
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