Re: Tegra DRM device tree bindings

On Tue, Jun 26, 2012 at 04:02:24PM +0300, Hiroshi Doyu wrote:

Hi Thierry,

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

quoted

* PGP Signed by an unknown key

Hi,

while I haven't got much time to work on the actual code right now, I
think it might still be useful if we could get the device tree binding
to a point where everybody is happy with it. That'll also save me some
time once I get to writing the code because I won't have to redo it over
again. =)

So here's the current proposal:

	host1x {
		compatible = "nvidia,tegra20-host1x", "simple-bus";
		reg = <0x50000000 0x00024000>;
		interrupts = <0 64 0x04   /* cop syncpt */
			      0 65 0x04   /* mpcore syncpt */
			      0 66 0x04   /* cop general */
			      0 67 0x04>; /* mpcore general */

		#address-cells = <1>;
		#size-cells = <1>;

		ranges = <0x54000000 0x54000000 0x04000000>;

		status = "disabled";

		gart = <&gart>;

...

quoted

output and hooks up a static EDID block with the LVDS output. There is
also a carveout property which might be a better replacement for the
"crippled" GART on Tegra20. Alternatively the CMA might work just as
well instead.

The Plutux can be described like this:

	host1x {
		carveout = <0x0e000000 0x02000000>;

As discussed in the following ML thread previously, the necessary info
related to the "gart" would be got from the standard IOMMU API(or
something above layers, DMABUF or TTM?). So I don't think that we need
to refer to "gart" and "carveout" here in the end.

http://lists.linuxfoundation.org/pipermail/iommu/2012-June/004266.html

Yes, if IOMMU or some layer above can provide the same information, then
that is certainly better than explicitly referencing it in the DT.

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

Thierry