PCI DMA Address
From: ina (celina.miranda_at_eazix.com)
Date: 04/29/04
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Date: 28 Apr 2004 23:39:25 -0700
Hi,
I need to create a driver for a PCI camera device that uses DMA to
transfer the captured images. The system that i use is an x86 board
that has 128M of RAM, I reserved the top of the physical RAM during
bootup by passing "mem=100".
In my driver i claimed the reserved memory by using ioremap call:
void* pAdd = ioremap(0x6400000,(1280x1024))
This is the memory where the PCI device should DMA the captured data.
My question is how do I tell the PCI device the DMA address? I know
that inorder for the PCI device to access the DMA address correctly, i
have to convert the return value of ioremap into a bus address. How do
i do this? I already used:
virt_to_phys(pAdd)
but this doesn't seem to work.
I read somewhere that the output of ioremap cannot be directly used
for virt_to_phys function call, but I'm not really sure...
Thanks,
Ina
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