Re: Tegra DRM device tree bindings

[Thierry Reding <thierry.reding-RM9K5IK7kjKj5M59NBduVrNAH6kLmebB@public.gmane.org>]

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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 <thierry.reding-RM9K5IK7kjKj5M59NBduVrNAH6kLmebB@public.gmane.org> wrote:
> 
> > * 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>;
> ...
> > 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

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