Re: Possible issue with dangling PCI BARs

[Ivan Kokshaysky]

On Fri, Dec 14, 2007 at 07:51:06AM +1100, Benjamin Herrenschmidt wrote:
> If the device is behind a P2P bridge and the BIOS has set the windows of
> that bridge so tightly that there is no room to allocate the MMIO BAR,
> then a full disable/full enable would fail on a device that would
> otherwise work using only PIO.

It won't be a problem with separate io/mmio enable.

> However, I'd be curious to see that happening in practice :-)
> 
> But I think it's fair enough to do an IO only / MEM only approach. I've
> seen cases where IO is just not useable because of other constraints and
> so I expect the MEM-only case to be more common, especially on non-x86.

Everybody wants MEM if it's available - it's just faster :-)
So I guess a common case will be

	if (pci_enable_device_mmio(dev)) {
		/* failed, fallback to IO */
		if (pci_enable_device_io(dev))
			return -ENODEV;
		...
	}

Ivan.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/