I'm using the 460sx (440 core) so no snooping here. What
I've done is reserved the top of memory for my driver. My
driver can read/write the memory and I can mmap it just
fine. The problem is I want to enable caching on the mmap
for performance but I don't know / can't figure out how to
tell the kernel to sync the cache after it gets dma data
from the device or after i put data into it from user space.
I know how to do it from regular devices, but not when I've
allocated the physical memory myself. I suppose what I am
looking for is something akin to dma_sync_single cpu/device.
In my device driver, I am allocating the memory like this,
in this case the buffer is about 512MB.
vma->vm_flags |= VM_LOCKED | VM_RESERVED;
/* map the physical area into one buffer */
rc = remap_pfn_range(vma, vma->vm_start,
(PHYS_MEM_ADDR)>>PAGE_SHIFT,
len, vma->vm_page_prot);
Is this going to give me the best performance, or is there
something more I can do?
Failing that, what is the best way to do this (i need a very
large contiguous buffer). it runs in batch mode, so it
DMAs, stops, cpu reads, cpu writes, repeat ...
thanks
ayman
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