Problems with dma_mmap_writecombine on mach-pxa

["Frank Buss" <fb@frank-buss.de>]

I'm trying to use the pxafb driver on mach-pxa, but I can't mmap the
framebuffer memory. I can access it from the driver, filling the entire
screen, but when I access the pointer returned from mmap from a user space
program, the following two things happens:

- the vm_pgoff is ignored and I get the start of the internal buffer, which
caused writing to the palette and DMA descriptors

- when I change the location of the framebuffer to the start of the internal
buffer, I can write to the screen, but only to the first 4 k; any write
after this address is ignored, but no segfault is generated.

Any ideas what I can do to find the reason? I don't think that it is a
kernel bug, but perhaps a wrong configuration for my platform.

-- 
Frank Buß, fb@frank-buss.de
http://www.frank-buss.de, http://www.it4-systems.de