Re: [RFC] Changing pci_iounmap to take 'bar' argument

[Linus Torvalds <torvalds@osdl.org>]

On Thu, 26 May 2005, Benjamin Herrenschmidt wrote:
> 
> 	foo = pci_iomap(dev, bar, pci_resource_len(dev, bar));

Btw, this kind of code should be just

	foo = pci_iomap(dev, bar, 0);

because the third argument is _not_ a length, it's a _maximum_ length we 
need to map, with zero meaning "everything" (as does ~0ul, of course, but 
zero is obviously easier).

The only people who want to use non-zero are things like frame-buffers
that might have hundreds of megabytes of memory, but the kernel only needs
to map the actual thing visible on the screen.

> And in a completely different function, a simple
> 
> 	pci_iounmap(dev, foo);
> 
> It may be simpler indeed for me to actually only complicate the ppc &
> ppc64 pci_iounmap() implementation and have it compare the virtual
> address against known PCI IO spaces...

Yeah. It shouldn't be a problem on 64-bit architectures, and even on 
32-bit ones the IO-port range really _should_ be fairly small, and a small 
amount of special casing should hopefully fix it.

A lot of architectures end up having to separate PIO and MMIO anyway,
which is - together with hysterical raisins, of course - why the existing
interfaces just assumed that was possible.

		Linus
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