On Tue, Jun 26, 2012 at 08:48:18PM -0600, Stephen Warren wrote:

On 06/26/2012 08:32 PM, Mark Zhang wrote:

quoted

quoted

On 06/26/2012 07:46 PM, Mark Zhang wrote:

quoted

quoted

quoted

On Tue, 26 Jun 2012 12:55:13 +0200
Thierry Reding [off-list ref] wrote:

...

quoted

quoted

I'm not sure I understand how information about the carveout would be
obtained from the IOMMU API, though.

I think that can be similar with current gart implementation. Define carveout as:

carveout {
        compatible = "nvidia,tegra20-carveout";
        size = <0x10000000>;
};

Then create a file such like "tegra-carveout.c" to get these definitions and

register itself as platform device's iommu instance.

The carveout isn't a HW object, so it doesn't seem appropriate to define a DT
node to represent it.

Yes. But I think it's better to export the size of carveout as a configurable item.
So we need to define this somewhere. How about define carveout as a property of gart?

There already exists a way of preventing Linux from using certain chunks
of memory; the /memreserve/ syntax. From a brief look at the dtc source,
it looks like /memreserve/ entries can have labels, which implies that a
property in the GART node could refer to the /memreserve/ entry by
phandle in order to know what memory regions to use.

That doesn't work, unfortunately. The /memreserve/ label isn't even
stored in the DTB. Even DTC throws an error when you try to reference
the /memreserve/ by label.

Thierry