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SubjectRe: [PATCH 05/14] lib: Add I/O map cache implementation
On Thu, Jan 10, 2013 at 06:26:55PM +0000, Arnd Bergmann wrote:
> On Thursday 10 January 2013, Thierry Reding wrote:
> > I don't understand how this would help. The encoding is like this:
> >
> > [27:24] extended register number
> > [23:16] bus number
> > [15:11] device number
> > [10: 8] function number
> > [ 7: 0] register number
> >
> > So it doesn't matter whether I use separate areas per bus or not. As
> > soon as the whole extended configuration space needs to be accessed a
> > whopping 28 bits (256 MiB) are required.
> >
> > What you propose would work if only regular configuration space is
> > supported. I'm not sure if that's an option.
>
> I mean something like:
>
> struct tegra_bus_private {
> ...
> void __iomem *config_space[16];
> };
>
>
> void tegra_scan_bus(struct pci_bus *bus)
> {
> int i;
> struct tegra_bus_private *priv = bus->dev->private;
>
> for (i=0; i<16; i++)
> priv->config_space[i] = ioremap(config_space_phys +
> 65536 * bus->primary + i * SZ_1M, 65536);
>
> ...
> }

Okay, I see. It's a bit kludgy, but I guess so was the I/O map cache.
It'll take some more time to work this out and test, but I'll give it
a shot.

Thierry
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